Preheat your oven to 350°F (175°C). Line a cupcake pan with 12 cupcake liners. This is crucial for easy removal and even baking.

Sift together the flour, cocoa powder, baking soda, and salt. This step prevents lumps and ensures a smooth batter.

In a separate bowl, whisk together the buttermilk, vinegar, and vanilla extract. Let it sit for a minute or two – the vinegar activates the baking soda.

In a large bowl, cream together the softened butter and sugar until light and fluffy. I usually do this for about 3-5 minutes with an electric mixer.

Beat in the eggs one at a time, mixing well after each addition.

Divide your batter in half. Add red gel food coloring to one half until you reach your desired deep red color. Start with a small amount and add more gradually.

Gradually add the dry ingredients and wet ingredients alternately to both the red and plain batter, beginning and ending with the dry ingredients. Mix until just combined – don’t overmix!

Spoon equal amounts of plain and red batter into each cupcake liner, creating a marbled effect. You can use a toothpick or knife to swirl the batter a bit more.

Bake for 18–20 minutes, or until a toothpick inserted into the center comes out clean.

Let the cupcakes cool completely in the pan before frosting. This prevents the frosting from melting.

Beat the cream cheese and butter together until smooth and creamy. Gradually add the powdered sugar and vanilla extract, beating until light and fluffy.

Combine the raspberry preserves (and optional food coloring) in a separate bowl. I find a spatula helps best here.

Combine the cream cheese frosting and raspberry mixture in a piping bag fitted with a large star tip (or a ziplock bag with a corner snipped off). Pipe the frosting onto the cooled cupcakes, creating a swirl.