Ok - so when it is really hot in my non-ac-ed apartment, and it is the mid-90s and very humid outside, I don't feel like baking.
So...thankfully I had a box of brownie mix in the cupboard - I know - it was quite a shock to my system too.
But, I took my box of 8x8 pan size, Betty Crocker, dark fudge, fudge like brownie mix and doctored it up.
I added Reece's pb chips to the batter. Then when it was done, I sprinkled some on top so others could tell what was in them. Just kinda pushed them down into it with a spatula and covered the warm brownies loosely with foil - so they would melt a little.
Other things you can add:
junior mints/york peppermint patties
mini baking chips
any kind of nuts
Be creative. Just because you use a box mix doesn't mean they have to be boring! :)