Peppermint Swirl Brownies

Step 1: Preheat the oven to 350°F with a rack in the center. Lightly grease an 8-inch square pan. Line the pan with a parchment sling and lightly grease the parchment.

Step 2: Make the peppermint swirl: In a small bowl, whisk together the cream cheese, sugar, milk, flour, peppermint oil, and food coloring until well combined and forming a pale green paste.

Step 3: For a striped or feathered finish, transfer the peppermint swirl topping to a zip-top bag or a piping bag fitted with a 1/2-inch round tip. For a simpler finish, set the topping aside.

Step 4: Make the batter: In a medium bowl or the bowl of a stand mixer fitted with the flat beater, beat the eggs, cocoa, vanilla, and salt to form a thick, uniform paste, scraping the bowl as needed.

Step 5: In a large saucepan over low heat, or in a medium microwave-safe bowl, melt the butter. Add the sugar and whisk to combine. Continue heating briefly, or microwave, just until the mixture is hot but not bubbling, about 110°F to 120°F. It will become shiny as you stir. The sugar will not dissolve fully.

Step 6: Add the cocoa mixture to the sugar mixture and whisk until well combined.

Step 7: Add the flour and whisk until well combined. The batter should be smooth and shiny.

Step 8: Transfer the batter to the prepared pan and spread it into an even layer. A small offset spatula is helpful.

Step 9: Add the peppermint swirl: If the filling is in a zip-top bag, snip the corner to make an opening about 1/2 inch wide. Using the zip-top bag or piping bag, pipe five to six evenly spaced stripes of filling across the surface of the brownies.

Step 10: Use a butter knife or wooden skewer to draw alternating lines perpendicularly through the peppermint stripes, pulling them into a feathered pattern. For a simpler finish, dollop the mixture on top of the batter and gently swirl it with a butter knife or wooden skewer to create a marbled effect.

Step 11: Bake for 28 to 32 minutes, until the edges feel set and a toothpick or the tip of a sharp knife inserted into the center comes out with moist crumbs clinging to it but no raw batter. A digital thermometer inserted in the center should register 205°F when the brownies are done.

Step 12: Remove the brownies from the oven and let them cool completely in the pan on a rack. Use the parchment to lift them from the pan and transfer them to a cutting board before slicing.

Step 13: Store leftover brownies in an airtight container at room temperature for several days, or freeze them for longer storage.