This makes a small batch of lightly sweet cookies. Double it to make more. If at any point the dough seems too sticky, pop it into the fridge for 5-10 minutes to firm up a bit. Or dust your parchment paper and cookie cutters with flour.
Place all ingredients into a bowl and use your hand to mix together to form a dough. (If the dough is a little crumbly, be sure that it's throughly combined and then if it's still crumbly, add 1/2-1 tablespoon additional liquid until it comes together.)
Make a flattened disc of dough and wrap in plastic. Refrigerate while the oven preheats.
Preheat the oven to 375°F and line two baking sheets with parchment paper.
Roll the dough ¼-inch thick between two pieces of lightly floured parchment paper. (The flour will ensure that the cut outs are easy to move.)
Cut out the dough with a cookie cutter and transfer to the prepared baking sheets. Bake for 7-9 minutes, until lightly browned around the edges. (If for some reason the cut outs are hard to transfer, place the rolled out dough with the stamped shapes into the fridge for a few minutes to firm up.)
Remove from the oven, let cool on the baking sheet for a minute, and transfer to a wire rack to cool completely.
Make the icing if using: Stir the ingredients together in a small bowl. You want it to be able to spread easily on the cookies and not be too thick. If you place some on the cookies and it runs right off, add a little more powdered sugar. If it's too thick to spread, add a drop or two of milk. You can color the icing with a drop of food coloring if desired.
Use a small butter knife or paintbrush to spread on the icing or pipe on as desired. If adding sprinkles or other decorations, add them to the iced cookies right away before it dries.
Store prepared cookies in an airtight container at room temperature for 3-5 days.
Gluten-Free: Use this gluten-free cup-for-cup style flour.
Dairy-Free: Use plain unsweetened nondairy milk in place of dairy milk. Use coconut oil, just softened (so not totally liquid, but softer than when it comes out of the jar at room temp). I tested it with about 10 seconds in the microwave in a heat-safe bowl.
If the dough sticks after you initially chill the dough and roll it out, cut out the shapes and put it back into the fridge without trying to get the shapes out so it firms up more. Let the sheet pan chill for 10 minutes, then use a flat knife to pop up the shapes.
If the dough is a little crumbly, be sure that it's throughly combined and then if it's still crumbly, add 1/2-1 tablespoon additional liquid until it comes together.
You can use whole-wheat pastry flour, white whole wheat flour, or half all-purpose and half whole-wheat. The cookies will be darker in color, but the results will otherwise be the same.
To make this dough ahead: Store it in the fridge wrapped in plastic wrap for up to 24 hours. It will need to sit at room temperature for about an hour to soften up, or you can remove it from the plastic, put it onto a plate, and microwave for 5-10 seconds.