Preparation Steps

• Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners.
• In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
• In a large bowl, beat the butter and sugar together until light and fluffy. Add the eggs one at a time, mixing well after each. Stir in the vanilla.
• Gradually add the dry ingredients to the wet ingredients, alternating with the milk, starting and ending with the flour mixture. Mix until just combined.
• Separate one-third of the batter into another bowl and mix in the cocoa powder to create the chocolate batter.
• Fill each cupcake liner with a mixture of the vanilla and chocolate batters to create a marbling effect, using a toothpick to swirl gently.
• Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool before serving.