This is my favorite brownie recipe:
Preheat 350 degrees
1) Combine until well mixed
- 1 cup Butter, melted
- 2 1/4 cups brown sugar
- 2 eggs
2) Combine and add to step 1
- 2 cups + 1 TBL flour
- 1 tsp. salt
- 1 tsp. vanilla
- 1/2 cup chopped pecans (optional)
3) Melt while stirring in a pot
- 12 oz chocolate chips
- 14 oz condensed milk (the thick sweetened stuff, not the milk for tea)
- 2 TBL butter
4) Spread the step 2 flour mixture in a 9x13 or 10x15 pan (reserve some if desired)
5) Pour chocolate mixture over the dough, swirl for design or dot with reserved dough
6) Bake 30-35 minutes until golden but make sure chocolate doesn't burn
7) Cool completely before cutting (but these taste really yummy when all warm and gooey).
ETA: Whoops! Sorry, I didn't catch the part where you already have mix for this occasion. If it is for adults, I like to sub in some creme de menthe or kahlua for an extra kick of flavor. I also love mixing in the baking chips they make of peanut butter, butterscotch, etc. or swirl in some jam.