dough for the crust
Add all-purpose flour to a large bowl. Add cold butter cubes. Using your fingertips, rub the butter into the flour mixture until there are no lumps or chunks of butter left. You can also use a blender or food processor to make the dough. Add the lemon zest, pinch of salt and baking powder. Stir to combine using a spatula. In a separate bowl beat together eggs, egg yolks, and sugar to get a fluffy, pale mixture. Mix for about 2 - 3 minutes. Add the egg mixture to the flour mixture and knead until it all comes together, for about 30 seconds. Don't overwork it. It should remain crumbly. Divide the dough in half.
roll out the dough
Dust your working surface with flour. Place a sheet on parchment paper over the dusted surface. Place one half of the dough in the center of the parchment paper and cover with another sheet of parchment paper. Using a rolling pin, roll the dough to approximately 1/2 cm (1/4-inch) thickness. Repeat the process with the remaining half of the dough. Place each dough on a separate tray or baking sheet (lined with parchment paper) and place in the fridge for 1 hour or in a freezer for 30 minutes.
roll out the dough again
Remove the dough from the fridge (or freezer) and roll it onto 2 - 3 mm (1/10) inch thickness. Transfer half of the dough to a tart tin (28 cm / 11 inch). Prick the dough with a fork and trim the dish of any extra dough or run a rolling pin over the top to remove excess dough.
add the marmalade and bake
Fill the pastry shell with high-quality apricot marmalade. Cut 1 or 1.5 cm (1/2 inch) stripes from the rest of the dough and create a desirable lattice finish on top of the marmalade. Place in the preheated oven. Bake for about 10 - 15 minutes at 180 °C / 355 °F, then lower the heat and bake for another 30 minutes at 175 °C / 345 °F.
Let the baked apricot crostata cool then transfer to a nice serving plate. Optionally sprinkle with some icing sugar and serve. Store any leftovers in an airtight container at room temperature for up to 3 - 4 days.