Step 1

Adjust the oven rack to the lower-third position and preheat the oven to 350°F (177°C). Line the bottom and sides of an 11×7-inch baking pan with parchment paper, leaving an overhang on the sides to easily lift the bars out of the pan. Set aside.

Step 2

Melt butter and semi-sweet chocolate together in a medium saucepan on medium heat, stirring constantly. Remove from heat and let cool to room temperature, about 15 minutes. You can place the melted chocolate/butter mixture into the refrigerator for a few minutes to speed this up, if desired. Don’t refrigerate too long, as the butter will start to re-solidify.

Step 3

Whisk sugar into cooled chocolate/butter mixture. Add in the eggs one at a time, whisking after each addition until combined. Whisk in the vanilla, and then gently fold in the flour and salt. Pour batter into prepared pan, reserving about 1/4 cup of batter (doesn’t have to be exact).

Step 4

Using a handheld mixer or stand mixer fitted with a paddle attachment, beat the cream cheese on medium-high speed in a large bowl until smooth and creamy, about 1 minute. Beat in the sugar, egg yolk, peppermint extract, and 2 drops of food coloring until completely smooth, about 1 minute. Feel free to add more green food coloring, if desired. Fold in the mini chocolate chips.

Step 5

Dollop spoonfuls of the cream cheese mixture on top of the prepared brownie batter. Spoon remaining 1/4 cup of brownie batter on top. Glide a knife through the layers, creating a swirl pattern. Add more mini chocolate chips on top, if desired.

Step 6

Bake brownies for 30–35 minutes, or until a toothpick comes out mostly clean with just a few moist crumbs. I recommend tenting the brownies with aluminum foil after about 20 minutes to protect the top from over-browning. Remove from the oven and place the pan on a wire rack. Cool brownies completely.

Step 7

Lift the brownies out using the parchment paper overhang on the sides. Cut into squares.

Step 8

Cover leftover brownies and store at room temperature for up to 1 day or in the refrigerator for up to 1 week.