Preheat oven to 180C
Mix the eggs, sugar, vanilla, and lemon zest together
Add the melted butter and mix well
Add your flour and baking powder and mix all until the dough is soft but not sticky
Spread half the dough in a rectangular baking tray ( you can use any size you want depending on how thick you want it to be)
Make sure the dough is smooth, poke it with a fork and bake it in the oven for 10 mins or until it is golden brown
Place the rest of the dough in the freezer so it crumbles easily
Remove it from the oven, spread the jam and crumble the rest of the dough on top
Bake in the oven for another 15-20 min or until the top has turned into a dark golden brown color
Remove, let cool and slice