I picked so many berries this year that after I got them home and washed them (and double checked for any stems), I froze most of them so they would keep longer. So my first step was to let them thaw some.
Combine the softened butter, sugar and vanilla and blend together until well combined. Then, add in the flour, baking powder and salt. Stir until a crumbly dough begins to form.
Lightly butter a pie pan and fill with the berries and lemon zest. Then, sprinkle the crumble top all over the berries. Bake at 375°F for 32-35 minutes, until the berries begin to bubble and the crumble top begins to brown.