For a birthday party, Annelies and I were asked to make a special cake.
After some brainstorming sessions, we came up with the Hot Tub Coffee Cup idea, since both the birthday ladies love coffee and go to the wellness together on a regular basis.
It is a HUGE cake though, so if you are having a small party, I suggest you make it with smaller cakes (dimensions of our cake: diameter at top = 25 cm, height: 18cm)
I hope you like it as much as they did!
Step 1: Preparation and Ingredients
We baked the cakes in advance and put them in the freezer until it was time to decorate.
If you prefer to bake them right before decorating, be carefull that they are completely cooled down before filling them with buttercream.
What you need:
- 3 cakes:
- 18 cm diameter: vanilla cake
- 23 cm diameter: chocolate cake
- 30 cm diameter: vanilla cake
TIP 1: We gave the middle cake a different flavour and colour to get a beautiful section when cutting the cake.
If you want a different size/model of coffee cup, feel free to use different cake dimensions. I would suggest not to make the upper cake way bigger than the bottom layer, since the weight of the cakes can be quite heavy to support.
TIP 2: You can replace the cakes by sponge-cake if you want to make it less heavy. I personally prefer the taste of cake. To make my cakes as light as possible, I beat the sugar with the egg yolks until they are airy and the colour has lightened significantly. Then I add vanilla extract and soft butter, wisk it together, add the sifted self raising flour and then add my beaten egg whites. Lighter cake, but with more flavour than sponge-cake in my opinion.
- Buttercream: We flavoured it with coffee to stay in theme.
Depending of the thickness of the layers, you will need more/less buttercream. We made approximately 2kgs of buttercream. A whole lot, but we used it all! It also depends on the recipe you use of course, the more voluminous the cream, the less you need. We followed our recipe for 3 cakes (diameter 26)
After making the buttercream, put it in a piping bag and leave it in the fridge.
- Sugar Paste
We used store-bought sugar paste in different colours.
- White sugar paste (approximately 1,5 - 2 kg)
- Green sugar paste (for details)
- Red sugar paste (for details)
- Pink sugar paste (for skin colour)
- Yellow sugar paste (for skin colour)
You can also make your own or work with white sugar paste only, then use colorants to make all those colours.
If you colour the paste yourself, use gel colorants, not the liquids, as they make your sugar paste softer and harder to work with. I really like the Wilton concentrated gel colorants.
- Pen with edible ink to for details (Eyes)
Step 2: Cutting the Cakes
1) If the edges are a little too dark, cut them off, the buttercream will cover up if it is not a perfect circle
2) Then, chop off the top of the cake. If you have a cake leveler (like a fretsaw for cakes - see picture), it comes in handy now. Otherwise, do it the old-fashioned way with a long knife.
3) Now, cut the cakes in half horizontally, so that they can be filled with buttercream. Again, this can be done with the cake saw, or with a knife. The cake saw makes it easier to have a perfectly straight cut. However, if your cakes are still frozen in the center/quite dense, the cord 'drags' a little, which doesn't give a perfect result.
Step 3: Filling the Cakes
1) Cut off the end of the piping bag and start piping the biggest cake. The best trick is to first make an outline and then fill up the inside. This doesn't have to look pretty, afterwards you use a spatula to straighten the buttercream.
2) Place the upper part of the cake on top of the buttercream layer and cover the top of the cake with buttercream.
3) Repeat the filling process for the middle cake. For the small cake, we only used one half because it came out quite high. So we did not fill that cake. If you want the double-layered small cake, fill it, but don't cover the top of the smallest cake in buttercream since this will be the bottom of the cake when flipped.
4) Now cut the profile until you get the desired shape, if there are straight corners, make them follow the curve of the cup, since this will make it easier to cover. Then cover the outside of the cakes in buttercream. Use a spatula to straighten the buttercream. (see tip).
TIP: It is easier to cover and straighten the outside of the cakes when it is placed on a turning surface. We don't have a cake - turner, so we used a turnable cheese plate. Make sure you place the cake in the middle of the plate.
In this way, you can measure if the cakes are approximately circles (place your hand at the side of the plate and use a finger to measure the distance from the side of the plate to the cake, then turn to see if the distance is the same at every point).
TIP 2: If possible, do step 1 and 2 one day in advance, in this way the buttercream can harden during the night in the fridge. This makes it easier for the sugar paste to hold, plus you can make the buttercream even smoother with a slightly warm spatula the next morning. If you don't have enough time to do this, put the cake in the fridge while you prepare the sugar paste.
Step 4: Sugar Paste Party
We chose to make little cartoons of the birthday girls.
First, we made the torso and the faces. To make the details on the face, make holes for eyes and nose, and glue sugar paste balls on them (you can do this with a little water - be careful because it makes the paste sticky)
If you make girls, draw lashes on the face before glueing the eyes on. For the mouth, carve the contour and fill with a thin sugar paste smile. The brows can be glued on without carving the contour first.
The most difficult thing is hairstyles. To get strings, we used a garlic press. The other birthday girl has short hair - for her we used dark coloured buttercream and put it in a piping bag with a grass decorating tip. But you can invent new ways to deal with the hairstyle you want to imitate.
After the heads are completely detailed, make the neck to connect head and torso (glue with water, if the head is too heavy, use a toothpick for extra stability). To hide the connection line between neck and torso, give the girls a necklace :).
To finish off, make some feet. It;s a small but funny detail to put in the "bubble foam"in your cake.
2) Coffee Cup
The most difficult task is to cover the entire structure in sugar paste. Don't worry if it doesn't come out perfect. Neither did ours, but no one noticed once the cake was finished.
To know how big your sugar paste should be to cover the whole coffee cup, measure the heigth of the cake (H) and the diameter of the small cake on top (D). The diameter of your sugar paste circle should be AT LEAST 2H+D.
The thickness is quite difficult to get right. Too thin and it will shear easily, too thick and it will be too heavy to stay up. We made it quite thick, I estimate 2-3mm. (But I must admit that it was a little too heavy so it broke a little on the back side of the cup. If you choose a straighter / smaller model of coffee cup this should be a little easier!)
If the sugar paste has the desired shape and thickness, gently roll it on a rolling pin. We did this together, and I can highly recommend having some helping hands so that the sugar paste does not break. From now on, handle quickly. Put the sugar paste on top of the cake, try to align the center of the paste with the center of the cake. Quickly press the sugar paste to the top and sides, and pull it up a little so that gravity does not tear it apart completely. Some little cracks are likely to appear, especially if you have not done this before. If you gently push the sides of the crack together, they will become less visible. Some tricks to stop gravity from tearing the sugar paste apart:
- Quickly cut all the redundant sugar paste off, so that the paste gets less heavy
- Smoothen the surface as quick as possible, then turn the cake upside down. If you wait too long, the sugar paste will start to fall apart, but if the sugar paste does not stick well enough, it will fall off when flipped. So work fast ;).
To smoothen the paste (before and after flipping the cake), you can use a fondant smoother, or just some kitchen paper and make circles to make the sugar paste smooth and well attached to the cake.
Lastly, make the ear of the cup and a boarder for on top of the cake. To make the ear hold its shape better, you can use a stiffening powder. Put the boarder straight onto the cake. Let the ear dry until the last moment. You can position some toothpicks for extra support.
TIP If you want to make the cup a little shiny/in a different colour, you can airbrush it. We used silver to give the cake an extra touch. You can also use edible silver powder and brush it on the cup. After colouring it, your fingerprints will be even more visible if you touch the cake, so be careful.
Step 5: Assembly
1) If you still have some buttercream left, you can use it to cover the top of the cake in order to create hot tub - foam.
We didn't have any buttercream left, so we made a mascarpone cream. You can replace this by any cream (cheesecake frosting,...). To give it a cappuccino effect, mix some brown colorant at the perimeter of the coffee foam.
2) Make the stencil for the cacao powder text / figure that you want to add. It's important to do this before you place the human figures, otherwise you might place them underneath a part of the stencil.
3) We held the stencil exactly where we wanted the text and then saw where we could put the human figures. After we put them into place, we sifted cacao powder over the stencil to write the text. Of course you can make the cacao text first and then put the figures into the cup. We chose to do it this way because then we could still add some structure with the mascarpone cream around the birthday ladies.
4) To present, put on a huge plate, accompanied by a big spoon.