1. Preheat the oven to 350°F.
2. Melt the chocolate in a double boiler. Add the butter, stirring until smooth.
3. In a bowl, whisk the eggs and sugar until pale.
4. Add the melted chocolate, stirring, then the flour.
5. Butter individual molds and fill halfway with batter.
6. Place a square of chocolate and 1 teaspoon of jam in the center.
7. Divide the remaining batter.
8. Bake for 10 minutes.
9. Remove from oven and serve.