Shortbread and the aforementioned Rice Krispy Treats will both satisfy your needs. Shortbread baked in a pan can be as thick as you want, and cuts nicely into squares. The Rice Krispy Treats can be made with cocoa powder added to give you a chocolate version of the same. Fudge would also serve your purpose.
Here are two recipes, one of my own creation, that can be made as thick as you desire. Just double the recipes. Hope something here helps you. Oh, and Sprout should be able to come through for you with the thick chocolate chip cookie. The uncle she spoke about used baking powder instead of baking soda, and added a bit of water to the standard recipe to create a more cake-like cookie. I don't have the recipe either, but will contact certain people to try and get it.
NO BAKE CHOCOLATE OATMEAL COOKIES
Ingredients:
1 stick butter
1/4 cup cocoa
1/2 cup milk
2 cups sugar
1 tbs. vanilla
1/2 cup peanut butter
3 cups rolled oats
Combine the butter, cocoa, milk, sugar, vanilla and peanut butter into a 2-quart saucepan. Bring to a gentle boil and cook for 1 minute. Add oats and mix well. Remove from heat.
Pour into a buttered cake pan.
Vanilla No-Bake Cookies
1 c Sugar
3 Egg yolks; slightly beaten
¼ cup milk
1 ts Vanilla
1/2 c Butter
1 cup rolled oats
1 1/3 c Coconut
1 cup Chopped pecans
Combine sugar, egg yolks, butter and vanilla. Cook and stir over medium heat until thickened, about 10 minutes. Remove from heat, add coconut and pecans. Pour into a buttered cake pan.
Seeeeeya; Goodweed of the North