01 - Preheat the oven to 350°F. In a mixing bowl, combine all-purpose flour, unsweetened cocoa powder, granulated sugar, and a pinch of salt. Cut in the cold, cubed butter until the mixture forms coarse crumbs.
02 - Add the egg yolk and 2 tablespoons of cold water to the flour mixture. Mix until the dough just comes together, adding an additional tablespoon of water if needed. Shape the dough into a disk, wrap in plastic wrap, and chill for 30 minutes.
03 - On a lightly floured surface, roll the chilled dough to fit a 9-inch tart pan. Press the dough into the pan, trim excess edges, and prick the base with a fork. Line with parchment paper and fill with baking weights or dried beans. Bake for 15 minutes. Remove the weights and parchment, and continue baking for another 10 to 12 minutes until the crust is firm. Allow the crust to cool completely.
04 - In a small saucepan, heat the heavy cream just below the boiling point. Pour the hot cream over the chopped dark chocolate in a heatproof bowl and allow it to sit for 1 minute. Add unsalted butter and stir until the ganache is smooth and glossy.
05 - Pour the ganache into the cooled tart crust and smooth the surface. Refrigerate for at least 1 hour until set.
06 - Arrange the halved strawberries over the set chocolate ganache.
07 - If desired, gently warm the apricot jam and brush it over the strawberries for a glossy finish.
08 - Slice and serve chilled or at room temperature.