Preheat your oven to 350°F (convection). In a bowl, mix room-temperature cream cheese with powdered sugar and vanilla extract until smooth. Split the mixture into three smaller bowls and tint each one with food coloring to make purple, green, and orange fillings.

In a stand mixer fitted with a whisk or paddle attachment, beat room-temperature butter with granulated sugar and brown sugar for 1–2 minutes, until pale and off-white. Mix in the egg, vanilla extract, and corn syrup until fully combined.

Add all-purpose flour, black cocoa powder, baking powder, and baking soda to the bowl. Fold or mix on low speed just until the dough comes together.

Place about two-thirds of the cookie dough into a parchment-lined 8x8-inch pan and spread evenly. Spread the colored cream cheese fillings over the dough, then top with the remaining cookie dough in chunks. Sprinkle extra granulated sugar on top if desired.

Bake the bars for 30–32 minutes, until set and lightly firm on top.

Let the cookie bars chill for 45–60 minutes before cutting into 4x4 squares.

Enjoy fresh, or store in a chilled environment for up to 8 days.