You will be amazed at how much butter goes into these things!
You can use any brownie recipe you like for the brownie part. Here's the one I use:
Quick and Easy Fudgey Brownies
4 bars unsweetened baking chocolate (I always use cocoa and oil, 3 Tbsp. cocoa and 1 Tbsp. oil equal one bar baking chocolate)
3/4 cup butter
2 c. sugar
1 1/2 tsp. vanilla
1 c. flour
1 c. chopped nuts (optional)
Heat oven to 350 degrees. Grease 13x9 inch pan. In a large microwaveable bowl, place chocolate and butter. Microwave at high 1-2 minutes or until chocolate is melted and mixture is smooth when stirred. Add sugar; stir with spoon until well blended. Add eggs and vanilla; mix well. Add flour and nuts; stir until well blended. Spread into prepared pan. Bake 30-35 minutes or until toothpick comes out almost clean. Cool on wire rack.
Let brownies cool completely.
1/2 cup butter, softened
2 cup powdered sugar
1/2 tsp. peppermint flavoring
2 Tbsp. milk
green food coloring (4 drops)
(These are also fun to make for Valentines Day with pink mint layer!)
Mix ingredients in order. Put mixture on cooled brownies. Refrigerate for 30 minutes.
1 cup chocolate chips
6 Tbsp butter
Cool, then spread over mint layer.