Preheat the oven to 350°F. Grease a cake pan with cooking spray or butter.
In a mixing bowl, combine all the filling ingredients and mix them well.
In a large mixing bowl, combine flour, sugar, baking powder, lemon zest, and a pinch of salt. Mix to combine.
Add sliced butter, egg, and vanilla extract.
Use your hands to combine the ingredients to form a coarse crumb mixture.
Place 2/3 of the mixture in the cake pan and lightly pat down.
Pour the filling over the crumb base and sprinkle it with the remaining crumb mixture.
Bake for 40 to 45 minutes.
Remove from the oven and let it cool for a couple of minutes before serving.
Serve and enjoy.