In a large bowl, add the flour, the white and brown sugar, the butter (cut into small chunks), and the egg.
Mix quickly with your hands (or an electric mixer) until the dough is smooth and well-blended. Shape it into a ball, wrap it in cling film and let it rest in the fridge for half an hour.
Prepare the cream in the meantime: melt the chocolate and butter in a bain-marie. Remove from heat and thoroughly blend in the mascarpone. Let stand for at least 30 minutes, then put in the fridge.
Roll out the dough on a floured surface to a thickness of approximately 5 mm. Line a tart pan (ideally one with removable sides) with the rolled pastry, and prick with a fork. Heat the oven to 180 °C, cover the bottom of the pastry with parchment paper, fill with chickpeas and bake for about 15 minutes, then remove the chickpeas and paper and bake another 12 minutes. Remove from the oven and let cool completely. Fill the crust with the cream.
Pour a generous amount of drained Amarena Fabbri cherries into the center of the tart. Before serving, drizzle with a bit of the cherry syrup