Slice and bake cookies are great because you can easily make the same pattern over and over again. If that pattern is eyeballs, even better!

These cookies were inspired by these polymer clay eyeball millefiori and these bullseye cookies I saw in Martha Stewart Kids magazine.

You can use either food colouring or cocoa to create the different colours in the eyes.

Step 1: Materials

For these cookies, you'll need:

dough from a favourite icebox cookie recipe (I like this one from SugaryWinzy* [edit: the site no longer exists but the recipe can be found through the internet archive wayback machine])
food colouring and/or cocoa
a rolling pin
parchment paper
baking sheets
cooling racks
a sharp knife, big and strong enough to cut the finished, partially frozen roll of dough

*I used half the amount of vanilla and added almost half a teaspoon of salt, but that's just personal preference. If you're going to use food colouring, you only need to make white dough. If you want to try using cocoa for the colour, make half the chocolate swirl SugaryWinzy describes: 3 tbsp cocoa mixed into 1 tbsp of melted butter and 1tbsp of milk, but don't add it to the dough yet.

Step 2: Colouring the Dough

We're going to work in decreasing quantity-of-dough-required, as well as from lightest to darkest to avoid having to clean the mixing bowl between colours.

Start by setting aside the majority of the dough to use as the whites of the eyes.

Dye the remaining dough to the iris colour. Don't worry about mixing it in perfectly, some variation in colour will just make it look even more interesting.

Set aside most of this dough and add a bit more colour to the remaining dough. This secondary colour will be used to add stripes in the iris.

Finally, the pupil: Set aside all the coloured dough, and take just a tiny bit of the white dough. If you have black food colouring, that would probably work well for this. I didn't, so I used a combination of extra dark cocoa powder and brown food colouring, which turned out fairly dark. If you're adding a lot of cocoa, it can help with the texture if you mix it with a little melted butter and milk first (the technique SugaryWinzy uses for pinwheel cookies — although we're making a much smaller amount of chocolate dough, so it's less important here).

If you're using all cocoa and no food colouring, follow the same colouring order, but add the cocoa/butter/milk mixture instead of food colouring. It's a bit sticky, but you could try using the cocoa/butter/milk without any dough to create as much contrast between the pupil and iris as possible.

Step 3: Forming the Eyes

On a clean surface, roll out the two iris colours into slabs of the same thickness (mine were about 1cm). Using a sharp knife, slice strips of the two colours and line them up in an alternating pattern. Squish it a bit to help it stick together. I think it looks kind of like bacon. If there are green eggs and ham there could be green bacon too, right?

Take some of the pupil dough and roll it into a log about 1cm in diameter. Lay it on top of the iris dough and roll the iris around the pupil. The stripes might fall apart a bit, but just squish it again and roll it to make it smoother. The important thing is that there is colour all the way around the pupil and that there are no gaps.

Finally, roll out a thick slab of white dough. Roll it around the iris and pupil.
If you're less lazy than me, you could also roll out a large thin slab and roll it up multiple times. This would probably give you less cracking, but I just tried to push it all back together at the end.

Give the whole thing a final roll to press the layers together and smooth the outside.

Step 4: Put Them in the Eyes-box

Wrap the logs up tightly, to keep air out. I used parchment paper and tinfoil, but you can also use waxed paper or plastic wrap. I've also read that a paper towel roll cut open can help the dough keep its round shape, but I just accepted the possibility of slightly misshapen eyes.

Put the dough in the freezer for at least half an hour, so it doesn't smear when you slice it.
You can definitely leave it for more than half an hour too; very convenient for when you need creepy cookies in the future.

Step 5: Slice and Bake

If the dough has been in the freezer for a while, it may need to thaw for a few minutes. It should be soft enough to cut but not squishy, or the design won't come out clearly.

Cut them to whatever thickness your recipe recommends, or to whatever will give you the crispiness or chewiness you want. I would recommend trying to make them all the same thickness — personally I couldn't always cut straight and some cookies had a thinner edge that got burnt quickly. Not ideal, but at least it gave me an excuse to eat some before photographing them?

Again, follow your recipe for baking temperature and time.