Prepare the brownie crust by mixing together flour, sugar, cocoa powder, baking powder, and salt. Add eggs, oil, and vanilla, mix until smooth. Line a muffin tin with cupcake liners and fill each halfway with batter.
Bake the brownie crusts at 350°F (175°C) for 5 minutes, then cool slightly.
For the cheesecake filling, beat cream cheese and sugar until smooth, then add egg, food coloring, and vanilla. Avoid overmixing.
Assemble the cheesecakes by placing an OREO cookie in each brownie crust and topping with cheesecake filling until ¾ full.
Bake at 350°F (175°C) for 18-20 minutes, cool slightly before transferring to a wire rack.
Chill the cheesecakes for at least 2 hours before serving.