Heat oven to 350 degrees F. Place foil or paper baking cups into 30 mini (1 1/4-inch) muffin pan cups. Set aside.
Combine sugar and 1/4 cup Cinnamon Sugar Butter Spread in large bowl; beat at medium speed until well mixed. Add buttermilk, 1 ounce melted chocolate, egg and vanilla; continue beating until well mixed. Reduce speed to low; add flour, baking soda and salt. Beat until well mixed. Add boiling water; continue beating until smooth.
Spoon about 1 tablespoon batter into each prepared muffin pan cups. Bake for 10 to 12 minutes or until toothpick inserted in center comes out clean. Cool completely.
Place 1/3 cup Cinnamon Sugar Butter Spread and melted chocolate in medium bowl. Beat at medium speed until creamy. Gradually add powdered sugar and cocoa, alternately with whipping cream, beating well after each addition until creamy.
Pipe or frost each cupcake with about 1 tablespoon frosting; sprinkle with decorator sprinkles, if desired.
To make ahead, bake cupcakes as directed; cool completely. Place unfrosted cupcakes in resealable plastic freezer bag. Freeze up to 2 months. Let stand at room temperature until thawed. Prepare frosting as directed. Frost cupcakes.