Preheat your oven to 350°
In a large mixing bowl beat your butter and cocoa powder together
In a separate bowl, whisk your eggs, sugar, and vanilla extract and mix into your butter mixture
Then mix in your flour and baking powder
Spoon your batter into your baking molds filling each heart only half full
Top each heart with about 5-6 M&M's
Bake for 10-12 minutes, then press a few more M&M's onto each heart brownie
Let partially cool, stretch the sides, and press up carefully onto the bottom of each heart to remove your brownie bites