Sift all-purpose flour, baking powder, and salt in a bowl and mix.
Use a smaller bowl to create a well in the flour mixture. (This prevents you from having to use multiple bowls for your wet and dry ingredients.)
Add eggs, sugar, milk, and oil, and vanilla. Mix all ingredients together with a hand mixer until well-combined.
Add lemon extract into batter and mix until combined.
Divide batter equally into 4 bowls (about 1 cup eacand add the gel food coloring to each bowl. I used pink, purple, orange, and blue.
Line a muffin tin with cupcake liners.
Add about 1-2 tablespoons of each color batter to the cupcake tins at a time. Do not mix the batter to keep the layered rainbow effect when baking!
Leave about ¾ of an inch of room in the cupcake tins to avoid overflow when baking.
Bake cupcakes at 350 degrees for 15-20 minutes.
Allow cupcakes to cool for about an hour before icing.