1. NOTE: you can also substitute 2 19 . 5 oz packages of brownie mix and follow the package instructions and then add the pecans. from scratch is much more delectable!
2. Whisk together melted butter and next 5 ingredients in a large bowl. Stir in flour and chopped pecans. Pour batter into a greased and floured 15 x 10 inch jelly roll pan.
3. Bake at 350 degrees F for 20-25 minutes or until wooden pick inserted comes out clean. Remove from oven and top warm cake with marshmallows.
4. Return to oven and bake 5 more minutes.
5. Drizzle Chocolate Frosting over warm cake. Cool completely.
6. Chocolate Frosting Recipe:.
7. Beat all ingredients together at medium speed with an electric mixer until smooth. You may have to add milk to obtain your desired consistency.