Preheat the oven to 425°F (220°C). Line a 12-cup muffin tin with paper liners and lightly spray them with nonstick spray.

Make the raspberry ganache centers: heat the heavy cream until steaming (don’t boil). Pour it over the chopped semisweet chocolate and let sit 1–2 minutes, then whisk until silky. Fold in the raspberry puree or seedless jam and stir in the butter if using. Spoon the ganache into a silicone mini muffin tray or small shallow mold and freeze until solid (about 1–2 hours).

In a heatproof bowl over a pot of simmering water (or in a microwave), melt 6 oz chocolate with butter until smooth. Remove from heat and let cool slightly.

Whisk together the granulated sugar, eggs, and extra yolks until pale and slightly thickened (about 2 minutes). Stir in the vanilla and salt.

Fold the melted chocolate mixture into the egg mixture carefully. Sift in the flour and cocoa powder and fold until just combined.

Spoon batter into liners, filling each about halfway. Press one frozen raspberry ganache disc into the center of each, then top with a spoonful of batter to cover.

Bake at 425°F for 12–14 minutes until the tops are set but the center is still soft.

Let cupcakes cool in the pan for 3 minutes, then carefully invert onto a cooling rack.

Dust with powdered sugar, garnish with a raspberry, and serve immediately with a scoop of vanilla ice cream or whipped cream.