Add butter and both sugars to the bowl of a stand mixer fitted with the paddle attachment and beat until smooth, about 3 minutes.
Add the eggs and vanilla and beat again until combined, scraping down the sides of the bowl if necessary.
Add the flour, baking powder, salt, and baking soda and beat again until a thick, uniform dough forms.
Fold in the dark chocolate chips. Cover and chill the dough for 30 minutes in the fridge.
Meanwhile, preheat the oven to 350℉ and line a large baking sheet or 2 medium baking sheets with parchment paper.
Using a cookie scoop, form 18 balls of dough and place them at least 3 inches apart on the baking sheet. Flatten each ball of dough to ¼ inch thickness, and press 4-5 of the M&Ms on the tops of each cookie ball.
Bake in the preheated oven for 11-12 minutes, or until just beginning to brown around the edges. Using your heart-shaped cookie cutter, immediately cut each cookie into hearts, discarding or saving the scraps for later. Allow the cookies to cool, then serve!
Notes
*Nutritional information includes the entire cookie before cutting into a heart.