• 1. Preheat the oven to 400 degrees. Line baking sheets with parchment, or grease well.
• 2. In a large bowl cream butter and sugar together until fluffy. Add egg and vanilla, and mix until combined.
• 3. Add buttermilk, mix until combined.
• 4. Add flour, salt, and cocoa, mix until combined.
• 5. Dissolve baking soda in hot water. Add mixture to the batter, and mix until liquid is incorporated.
• 6. Place batter in piping bag or in large ziplock (cut off corner, about 1/2 inch). Create heart shapes by piping two V-shapes - use about 1 tablespoon of batter per heart.
• 7. Bake for 8 minutes, or until just set - should not be crispy.
• 8. Allow to cool for a few minutes on the baking sheet, then transfer to cooling racks.

For the Buttercream

• 1. If using fresh raspberries, puree them in a blender with about 1/4 cup of water. Add to a small saucepan and cook on medium heat, stirring regularly, until liquid reduces and thickens. It should be about the texture of polenta/grits.
• 2. Press fruit through fine-mesh sieve, and set aside.
• 3. In a medium bowl, combine butter, powdered sugar, and raspberries -- either 1/4 cup of jam, or 1/4 cup of strained raspberry puree. Mix until well-combined. If too thick, add more puree or jam, if too thin, add more powdered sugar. (Err on the side of thick for this recipe, so the frosting does not ooze out of the whoopie pies).
• 4. Place frosting in piping bag or 1 gallon ziplock with corner cut out (about 1/2 inch). Pipe onto cooled heart cookie, and then top with another heart cookie.