In a small saucepan combine chocolate, cream, and butter. Stir over low heat until chocolate is melted. Transfer to a small bowl and let cool for 15 minutes. Cover and freeze about 1 hour, or until fudge-like consistency. Divide chocolate filling into 12 equal portions and roll into balls. Place in freezer.
For the cupcakes:
Preheat oven to 375 degrees F. Line a standard muffin tin with paper liners.
In a small bowl sift flour, cocoa powder, and salt. Set aside.
In the bowl of an electric mixer beat butter and sugar on medium for 2-3 minutes, until light in color and well combined. Beat in egg, food coloring, and vanilla. Alternately add flour mixture and buttermilk, beating on low speed after each addition just until combined. In a small bowl combine baking soda and vinegar. Stir into batter.
Divide half the batter among prepared cups. Place a ball of chocolate into center of each cup. Top evenly with remaining batter.
Bake 15-17 minutes, or until tops spring back when lightly touched. Serve warm or let cool completely. Cupcakes can be stored in an airtight container at room temperature for 2-3 days.