Preheat oven to 350°F. Grease and flour (or line with paper bake cups) twelve (2 1/2 inch) muffin cups ; set aside.
In a large saucepan, melt butter over medium heat. Remove from heat. Let cool for 5 minutes. Stir in sugar and cocoa powder until combined. Add egg and vanilla. Using a wooden spoon, beat lightly just until combined.
In a small bowl, stir together flour, baking powder, baking soda, and salt. Alternately add flour mixture and milk to chocolate mixture, beating by hand after each addition. Spoon batter into prepared muffin cups, filling each two-thirds full.
Bake for 15 to 20 minutes or until a toothpick inserted near the centers comes out clean. Cool in muffin cups on a wire rack for 10 minutes. Using a knife, loosen the edges; carefully remove cupcakes. Cool completely on a wire rack.
If cupcakes don't have paper liners, trim a thin slice from top of each cupcake so they will sit flat. Turn bottom side up. Place cupcakes 2 inches apart on wire rack set over waxed paper. (For cupcakes in liners, peel liners down but do not remove.) Spread 1 teaspoon of the strawberry jam over each cupcake.
Prepare Bittersweet Chocolate Ganache. Spoon ganache over cupcakes, making sure to coat all sides. Place a strawberry on top of each cake. Drizzle each strawberry lightly with ganache, letting the strawberry show through. Top cupcakes with chocolate curls.
BITTERSWEET CHOCOLATE GANACHE: In a medium saucepan, bring 1 cup whipping cream just to boiling over medium-high heat. Remove from heat. Add 10 ounces bittersweet chocolate, chopped (do not stir). Let stand for 5 minutes. Stir until smooth. Whisk in 3 tablespoons butter, 1 tablespoon at a time, whisking until ganache is smooth.