01 - Preheat the oven to 350°F.
02 - In a mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, granulated sugar, and salt.
03 - Add the cold, cubed unsalted butter. Using a pastry cutter or food processor, blend until the mixture forms coarse crumbs.
04 - Mix in the egg yolk and 2 tablespoons cold water. Stir just until the dough comes together, adding an additional tablespoon of water if necessary.
05 - Shape the dough into a disk, wrap in plastic wrap, and refrigerate for 30 minutes.
06 - On a lightly floured surface, roll out the dough to fit a 9-inch tart pan. Press the dough evenly into the pan, trim the edges, and prick the base with a fork.
07 - Line the crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes, remove weights and parchment, then bake an additional 10–12 minutes until firm. Allow to cool completely.
08 - Heat heavy cream in a saucepan just until it begins to simmer. Pour over the finely chopped dark chocolate in a bowl. Let stand for 1 minute, add unsalted butter, and stir until smooth and glossy.
09 - Pour the ganache into the cooled tart crust. Smooth the surface and refrigerate for at least 1 hour until set.
10 - Place the halved strawberries decoratively atop the set ganache.
11 - If desired, gently warm apricot jam and brush over the strawberries for a glossy finish.
12 - Slice the tart and serve chilled or at room temperature.