Step 1: Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners.
Step 2: In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt.
Step 3: Add the buttermilk, oil, egg, and vanilla to the dry ingredients. Mix until smooth and well combined.
Step 4: Divide the batter evenly among the cupcake liners, filling each about two-thirds full.
Step 5: Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let the cupcakes cool completely on a wire rack.
Step 6: Once cool, use a small knife to remove the center of each cupcake. Fill the hole with approximately 1-2 teaspoons of strawberry jam.
Step 7: Prepare the frosting by beating the butter until creamy. Gradually add powdered sugar, heavy cream, and pink gel food coloring until you reach a stiff but pipeable consistency.
Step 8: Fit a piping bag with a medium round tip. Pipe a vertical line down the middle of the cupcake. Pipe squiggly ‘brain’ folds on each side of the line.
Step 9: Optional: Lightly brush the brains with a little extra jam for a shiny, gory finish.