These are the best M&M cookies around! Rich, thick, and intensely chocolatey. Chewy softness for days. Perfect for any festive occasion or just an afternoon chocolate fix.
In a bowl, whisk the four, cocoa powder, baking powder, and salt. Set aside.
In a microwave safe bowl, melt chocolate at 50% power for 2 minutes, stir, and continue heating until melted, stirring each minute. (Alternatively do this in a bowl set over saucepan of simmering water stirring until melted.)
In a bowl, whisk together the eggs and vanilla. Sprinkle coffee powder to dissolve. Set Aside.
In the bowl of a stand mixer fitted with paddle attachment, beat butter and both sugars at medium until combined, 1 minute. Mixture may be gritty. Decrease to low speed, add egg mixture, and mix to incorporate, 1 min.
Add melted chocolate in a steady stream, mixing until combined, 1 minute, scraping down bowl and beater as needed.
With mixer still on low, add dry ingredients gradually and gently mix just until combined, without over beating.
With rubber spatula, fold in M&Ms. Cover bowl with plastic wrap and chill in fridge at least 1 hour or until scoop-able.
Adjust oven to lower middle position, at 350F. Line baking sheets with parchment paper.
Divide dough into balls about 1 1/2 inch in diameter. Set balls on lined baking sheets, about 2 inches apart. Slightly flatten dough balls.
Bake just until edges are begun to set but centers are still very soft, 8-9 minutes. Cool on baking sheets 10 minutes. Carefully transfer to wire rack and cool to room temp.