Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking pan or line it with parchment paper for easy removal.

In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.

In a separate bowl, cream together the softened butter and granulated sugar until light and fluffy—approximately 4-5 minutes.

Beat in the eggs one at a time, mixing well after each addition. Then stir in the vanilla extract.

Gradually add the dry mixture to the wet ingredients, alternating with the milk, starting and ending with the dry ingredients.

Divide the batter into bowls based on how many colors you want and add food coloring to each, mixing until you reach desired shades.

Spoon the colored batters alternately into the prepared pan. Use a knife or skewer to swirl the colors together gently.

Place the cake in the preheated oven and bake for about 30-35 minutes or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack. Once cooled, frost with whipped cream or your choice of frosting.