Two-Tone Tart

Method

1. Prepare the plain shortcrust pastry: in a bowl, combine butter, flour, and sugar; work with the paddle attachment, add whole eggs and egg yolks, gather the dough, then divide into two equal parts.
2. Prepare the cocoa shortcrust pastry: place one half of the dough back in the stand mixer, add cocoa powder, and mix until uniform. Form a ball, wrap both doughs in plastic wrap, and chill for at least 30 minutes.
3. Prepare the custard: in a saucepan, heat milk with lemon zest until it just begins to simmer. In another bowl, whisk egg yolks with sugar, then add flour (not starch, as this custard will be baked again). Temper with a little of the hot milk, then return to the heat with the remaining milk, stirring constantly until thickened.
4. Divide the custard in half: pour half into a bowl. To the other half, add chopped dark chocolate and stir immediately to melt. Cover both bowls with plastic wrap touching the surface, let cool slightly, then refrigerate for at least 1 hour.
5. Roll out the chilled plain and cocoa doughs separately to a thickness of 3–4 mm. Cut each into strips about 1 cm wide.
6. Weave the strips into a lattice pattern on a sheet of parchment paper to create the tart lid. (For a simpler version, alternate strips in a checkerboard pattern.) Place the lattice in the fridge to firm up for 10 minutes.
7. Using the leftover scraps of both doughs mixed together, roll out a disc and line the tart ring, pressing with your hands to form the base. Trim the edges. Fill with the plain custard, spreading evenly, and chill for 10 minutes.
8. Pipe the chocolate custard on top in a decorative pattern or spread with a spoon. Carefully place the lattice lid on top. Bake at 170°C (340°F) for 45 minutes, then at 180°C (355°F) for another 15 minutes until the surface is golden.
9. Let the tart cool before serving. Enjoy!