Preheat oven to 350 degrees and line a 9x13 baking dish with parchment paper

In a standing mixer, add the flour, sugar, and lemon zest and mix till combined.

Add in the butter and mix

Using your fingers or a fork, break up the butter into smaller pieces and mix

Add in the eggs and mix until a crumbly dough comes together

Press half of the dough into the bottom of the baking dish and set aside

In a large mixing bowl, combine the blackberries, lemon sugar, cornstarch and sugar and mix until combined

Pour the blackberry mixture over the crust and even it out with a rubber spatula

Crumble the remaining dough over the blackberry filling

Bake in the preheated oven for 35-40 minutes or until the crumble appears slightly golden brown

Pull the baking dish out of the oven and set aside to cool completely

Cut and enjoy!