The ganache filling is warned, only just set, and almost like custard, soft and smooth.
1 fully baked 9 inch tart shell, cooled to room temperature
1/2 cup red raspberries
5 ounces (145 grams) bittersweet chocolate (NOT semi sweet)
1 stick unsalted butter
1 large egg, at room temperature, stirred with a fork
3 large egg yolks, at room temperature, stirred with a fork
2 tablespoons sugar
1/4 cup red raspberries
Center the rack in the oven and preheat to 375. Fill the tart crust with the raspberries. Melt the chocolate and the butter in separate bowls either over simmering water or in the microwave. Allow them to cool until they feel only just warm to the touch. Using a small spatula, stir the egg into the chocolate, stirring gently in ever-widening circles and taking care not to agitate the mixture – you don’t want to beat air into the ganache. Little by little, stir in the egg yolks, then the sugar. Finally, still working gently, stir in the warm melted butter. Pour the ganache over the raspberries in the tart shell. Bake the batter for 11 minutes – that should be just enough time to turn the top of the tart shell, like the top of a cake. The center of the tart will shimmy if jiggled – that’s just what it’s supposed to do. Remove the tart from the oven, slide it onto a rack, and allow it to cool for about 10 minutes before serving. Scatter the fresh raspberries over the top of the tart.
Keeping: The crust can be made ahead, but the tart should be assembled as soon as the ganache is made. And while the tart is meant to be eaten soon after it comes from the oven, it can be kept overnight in the refrigerator and brought to room temperature before being eaten the next day. The filling will be firmer and denser, but still delicious.
Note: Keep the cooled crust, with the tart ring still in place, on the parchment-lined baking sheet. (The crust can be baked up to 8 hours ahead and kept at room temperature.)