This is an idea I got yesterday so these cookies are very new to me too! :)
I wanted to make something new for Christmas this year and I thought that nothing would be better than a surprise present! The surprise I am talking about is the jam I put inside the cookies, but you can put chocolate, nutella, pieces of apples or anything you want.

Step 1: Ingredients

125 gr (about a stick) cold butter
250 gr (2 cups) flour
2 egg yolks
100 gr (7/8 cup) icing sugar
vanillin or vanilla extract - I used a sachet that contains 0.5 gr of vanillin, it's probably a little more than a pinch. Whichever extract you use, only a little is needed to give flavour to your cookies.
a pinch of salt
food coloring
jam
optional: a bit of baking powder to make the cookies softer

With this dose, you can make about 20 cookies.

Step 2: Make the Dough...

Mix the flour with the cold butter and a pinch of salt.
Now add sugar, vanilla and the yolks (and a bit of baking powder if you want).
Mix all the ingredients until you have a compact dough.
Wrap it in plastic wrap and put it in the fridge for at least a half hour.

Step 3: Cut Squares

Your dough is ready to make cookies!
Flatten the dough with a rolling pin. I made it about 3 mm thick (0.11 inches).
Now cut out many squares and remove the rest of the dough. You can flatten it again and make other squares out of it but remember to keep some dough to make the decoration.
I made the squares with a cookie cutter but you can also make them simply cutting with a knife. My squares are about 4/5 cm (1.57 inches).

Divide them in 2 groups with the same number of squares so that you have both the top and the bottom for each cookie.

Step 4: Stuff With Jam

Take one group of squares and put some jam on it. Half a teaspoon in each cookie was more than enough for me.
Now take the other group of squares and put them on the ones with the jam to close them. You can add some water on the sides to help closing them and push a little.

Step 5: Decorate!

Your cookies are almost ready, now it's time to make the decoration!
Take the dough that was left and divide it in as many colors as you want to use. I divided it in 2 and made one red and the other one green with food coloring.
Once the colored dough is ready, take small pieces of it and make little strips to put on the cookies, as present laces. I also cut tiny stars with a toothpick to put at the center of the cookies, where the strips meet.

Step 6: Almost Ready...!!!

Bake at 180C (350F) for 10-12 minutes, adjusting time to compensate for the size of your cookies.
I made some holes on them with a toothpick to make sure that they don't burst.