Dissolve the instant coffee in a little bit of water(2 tsp).
With a mixer, beat the butter and powdered sugar until light and fluffy. Add milk, and dissolved coffee. Add egg yolks, one by one, while keep mixing.
Add slowly the flour, salt, and baking powder to make a dough.
Place the dough covered in plastic wrap in the fridge for about 30 minutes.
Take the dough out, place it on a floured surfaces, roll it about ¼ inch thick.
Cut the cookies in any shape you want.
Bake them on a parchment paper-covered cookie sheet at 350F for 10 minutes until the edges get slightly golden.
Instead of coffee, you can use cinnamon or vanilla.
Notes
If you want to make a larger batch of these cookies, you can double or triple the recipe as needed. Just be sure to mix the ingredients well and chill the dough in separate batches if necessary.
If you don't have a rolling pin, you can use a wine bottle or other cylindrical object to roll out the dough.
You can also make these cookies gluten-free by using a gluten-free flour blend instead of all-purpose flour.
If you're short on time, you can make the dough ahead of time and store it in the fridge for up to 3 days before rolling it out and baking it.
In terms of decorating these cookies, the possibilities are endless. You can use icing, frosting, sprinkles, or any other decorations you like. Just make sure to wait until the cookies are completely cool before adding any decorations, or they may melt or slide off.