Preheat oven to 425°F (220°C). Grease a 12-cup muffin tin or use liners.

Melt chocolate and butter together in a bowl over simmering water or in the microwave. Stir smooth.

In a separate bowl, whisk eggs, egg yolks, and sugar until pale and slightly thick.

Stir the chocolate mixture into the egg mixture. Add vanilla, then fold in flour and salt until just combined.

Spoon batter into liners, filling each cup about halfway.

Add 1 teaspoon raspberry jam or a raspberry in the center of each cup.

Cover jam with more batter so each cup is about three-quarters full.

Bake for 10–12 minutes. Tops should be set and edges firm but centers soft.

Let cool for 1–2 minutes, then run a knife around the edges and carefully remove the cupcakes onto plates.

Dust with powdered sugar if desired and serve warm.