This dough can be a bit crumbly initially. Use your hands to bring the dough together and add 1 -2 teaspoons of water if needed.
You want your dough to be about 1/4" thick. If it ends up thinner you will just have a crisper cookie which is totally delicious too and you can just decrease your baking time a bit too.
Use a 1 1/2 inch cookie cutter. I actually used my grandmother's old biscuit cutter. You can make the cookies bigger or smaller if you like, just by using a different size cutter.
You want to be careful not to put too much frosting on the cookie or your top cookie will slide off. I found it best to put on enough frosting so that it didn't quite come to the edge of the cookie. It gave it a little room to spread once the top cookie is placed on.