Line two baking sheets with parchment paper. Trace small heart shapes onto the paper using a cookie cutter or template, leaving space between each. Flip the parchment so the marks are on the underside.

Whisk together flour, cocoa powder, baking powder, and salt in a medium bowl.

In a large bowl, beat butter until creamy (1 minute). Add brown sugar and beat until fluffy. Mix in the vanilla extract and egg. Add buttermilk and red gel food coloring, blending until smooth.

Gradually mix the dry ingredients into the wet ingredients until just combined. Do not overmix.

Transfer the batter to a piping bag with a ½-inch round tip (or use a zip-lock bag with a corner cut). Pipe “V” shapes inside the heart outlines on the parchment.

Preheat the oven to 350°F (175°C) and bake for 10–12 minutes, or until centers are set. Let cool on the baking sheet for 10 minutes before transferring to a wire rack.

Beat together butter, cream cheese, and vanilla until smooth. Gradually add powdered sugar, mixing until fluffy.

Pair cookies by size and shape. Pipe filling onto the flat side of one cookie, leaving space around the edges. Top with another cookie (flat side down) and press gently.

Store in an airtight container in the refrigerator for up to 5 days. Bring to room temperature for 10 minutes before serving.