Pulse flour, cocoa, and sugar in a food processor until combined.
Add cubed butter and pulse until the mixture resembles coarse meal.
Whisk egg yolk and 2 tablespoons cream together then add to processor and pulse until dough just begins to clump.
Press dough into a 9-inch tart pan with a removable bottom and chill for 30 minutes.
Preheat oven to 375F or 190C and bake the crust for 15-20 minutes until set then cool completely.
Spread raspberry jam over the bottom of the cooled crust and arrange fresh raspberries in a single layer.
Heat 1 cup heavy cream in a saucepan until it reaches a simmer then pour over the chopped chocolate.
Let chocolate sit for 2 minutes then whisk gently until a smooth ganache forms.
Pour the ganache over the raspberries smoothing the top with a spatula.
Refrigerate for at least 2 hours or until the ganache is firm before serving.