In bowl of a KitcheAid mixer, stir together flour, sugar, and baking powder.
Fit the mixer with the paddle attachment, and add the eggs, egg yolk, butter and lemon zest.
Beat the ingredients together in the mixer until the dough starts to come together, until it almost forms a ball.
On a smooth surface, very gently form the dough into a ball. Wrap in plastic wrap and place in the fridge for one hour.
Preheat oven to 350°F. Remove dough from the fridge, remove ¼ of the dough, and roll the rest of the dough out with a rolling pin on a well floured surface until it's ⅛" thick.
Roll the dough on to the rolling pin, and transfer it to a tart pan.
Top dough with jam and spread it out evenly.
Cut strips from remaining dough, and make a lattice pattern on the crostata. Fold in the edges of the crostata over the lattices.
Bake crostata in the oven for about 30 minutes, or until dough is golden.
Remove from oven, let crostata cool completely (a few hours), slice and serve!