Preheat oven to 350°F. Line a 9x13” pan with foil and spray with cooking spray.
Cream brown sugar and butter in the bowl of an electric mixer fitted with a paddle attachment. Add eggs and vanilla and beat until combined. Add cocoa, baking powder, salt, and flour and mix. Carefully mix in red food coloring.
Press into prepared pan (dough is sticky, spray your hands with cooking spray to avoid it sticking to your hands).
Bake or about 23-25 minutes. (Be careful not to overcook - the center will still be jiggly when you take these out of the oven and they will finish cooking and firming up as they cool.) Cool completely before slicing into squares.
Optional garnish: melt white chocolate almond bark or white chocolate chips according to package directions. Drizzle over bars. Note: I’ve had trouble melting white chocolate chips lately, so I highly recommend using almond bark, Candiquik, or candy melts for this step.