Spray a 13-by-18-inch rimmed baking sheet with cooking spray. Whisk together the flour and baking powder in a medium bowl.

Beat in the vanilla and the lemon zest, lemon juice, orange zest and orange juice ... the rack and let it cool completely. 4. Make the Glaze: In a medium bowl, whisk all of the ingredients ...

Remove ½ cup of the glaze to a medium bowl. Stir in the food coloring to make a deep orange color. Pour the white glaze over the cake, spreading with an offset spatula to cover. Drizzle the ...