Prepare cupcakes according to box instructions, tinting the batter with green food coloring before baking. Cool completely.

Use a knife or cupcake corer to cut out a small hole in the center of each cupcake. Fill with red jam and replace the top piece.

Make frosting: beat butter until creamy, then gradually add powdered sugar, milk, and vanilla until fluffy.

Tint frosting with pink or red food coloring to resemble brain tissue.

Using a piping bag with a small round tip, pipe squiggly lines on top of each cupcake to look like brains.

Optional: add black gel icing between the 'brain folds' for a more defined zombie look.

Serve and watch your guests squirm as they bite into 'brains'!