• Preheat the oven to 350F and line a square 9x9 inch baking pan with parchment paper or grease the pan well with butter.

For the strawberry filling

• In a small mixing bowl stir together the diced strawberries, sugar, cornstarch and lemon zest until strawberries are well-coated. Set aside.

For the crumble crust

• In a medium mixing bowl whisk together flour, oats, sugar, brown sugar, baking soda and salt. Stir in melted butter and mix until fully combined, creating a crumbly mixture.
• Save 1 1/4 cups of the crumble crust mixture and set aside. Pour the rest of the mixture into the baking pan and press into an even, flat base layer with your hands.
• Pour the strawberries mixture including all the juices onto the crumble crust base layer in the pan. Spread the strawberry mixture into an even layer.
• Finally, sprinkle the 1 1/4 cups crumble crust mixture you saved over the strawberries layer, evenly coating them.
• Bake for 35-40 minutes until crumble crust topping is golden brown and strawberries are set (they may be bubbling).
• Remove from oven and let completely cool in the pan or they will fall apart if not completely cooled before cutting. You can also place them in the fridge to help cool faster.
• These will keep in the fridge for up to 4 days!