Preheat the oven to 350 degrees. Place 24 cupcake liners in 2 muffin tins.

In a medium bowl combine the flour, baking powder, and salt. Mix well and set aside.

In a large bowl cream together the butter and sugar.

Add in the eggs, lemon zest, lemon juice, and vanilla. Mix well.

Add half the flour mixture to the butter mixture and mix well.

Stir in the milk and mix until well combined.

Add the remaining flour mixture and mix until just combined.

Use a cookie scoop and fill the muffin tins 3/4 of the way full.

Bake for 22-25 minutes or until a toothpick inserted into the center comes out clean.

Cool completely on a wire rack.

To make the frosting place the butter in a large bowl. Using a hand mixer beat on medium high speed for 1-2 minutes or until fluffy and smooth.

Add in the powdered sugar, vanilla, and milk and beat on medium speed for 2-3 minutes or until light and fluffy.

Place 1 tablespoon frosting on top of each cupcake and smooth over the top.

Pour the red sugar into a shallow dish and the blue sugar into a second shallow dish.

Dip on side of the cupcake top into the red sugar then dip the other side into the blue sugar. Sprinkle yellow sugar in the middle. Gently press down on the sugar.

Serve with a wooden spoon if desired.