Each of these rich and fudgy oversized brownie cookies is hiding a bright white peppermint patty center inside! This is a one bowl cookie recipe made with straightforward pantry ingredients, easy to whip together in just about an hour. (Prep time includes shaping the cookies.)
Melt butter and chocolate. Bring 1 inch of water to a rolling boil in a pot. In a large mixing bowl that fits over the mouth of the pot without touching the water, combine butter and chopped chocolate. Place the bowl on top of the pot, turn off the heat, and stir the butter and chocolate together until melted.
Add brown sugar and eggs. Vigorously whisk in the brown sugar until smooth and no lumps remain. Whisk in the first egg, making sure it's fully incorporated. Then add the second egg along with the peppermint extract and whisk for at least 60 seconds until fully combined.
Sift the dry ingredients. Use a wire mesh strainer to sift the flour, cocoa powder, baking soda, and salt into the dough. Switch to a spatula and gently fold the dry ingredients into the chocolate just until combined, making sure to scrape all the way to the bottom of the bowl as you stir. Cover the dough and chill in the fridge for 30 minutes.
Preheat oven to 350°F. Line a cookie sheet with a silicone mat or parchment paper.
Shape the cookies. Use a #40 (1½ tablespoon) cookie scoop to portion out 26 cookie dough balls. Sandwich the Peppermint Patties between two flattened cookie dough balls. Smush and fold the edges around the Peppermint Patty to seal it in place and create a round ball, then roll it between your hands to smooth out the seams. Note: Try to remember which direction the patty is lying inside the cookie so you don’t accidentally end up baking it vertically!
Bake. Bake 11-12 minutes until cookies are puffy, but still look slightly underdone. Scoot into shape using a round cutter or upside down glass if you want to while they're still hot. Let cool on the sheet tray for a few minutes, then transfer to a rack to finish cooling completely.
RECIPE NOTES
If you're one cookie dough ball short, pinch off a small amount from the others to make the final dough ball. If you have one cookie dough ball too many, divide it up amongst the others.
This cookie dough will keep in the fridge for a week before scooping, just let it warm up at room temperature bit first.
When baking these peppermint brownie cookie dough balls from frozen, add 2-3 minutes to the bake time or let them defrost for about 30 minutes before baking.
Store peppermint patty brownie cookies at room temperature in an airtight container for up to 2 weeks, or in the freezer for up to 3 months. Defrost frozen cookies on the counter, or in a 250°F oven if you're in a rush.