For the strawberries, add your berries, ⅓ cup of sugar, and lemon zest to a pot, and place over medium heat. Breaking up the berries with a spoon as they cook down, to help release moisture

Once the strawberries have softened and broken down a bit, add in the lemon juice and bring to a boil

In a small bowl, stir together the cornstarch and 2 tbsp of water to make a slurry. Then stir it into your strawberry mixture. Cook for 8 minutes until reduced and lightly thickened, stirring constantly

Immediately remove your strawberry mixture from the heat and pour it into a heat-safe bowl to cool to room temperature (about 35 minutes). You can make this in advance and store it covered in the fridge until you’re ready to use it

Make your crumb topping by stirring together the ½ cup of flour and ½ cup of sugar in a bowl. Add in the cold cubed butter, rubbing it in until it resembles coarse crumbles. Place in the fridge while you make your batter

For your cake, in a new bowl, combine 1 ½ cups of flour, ½ cup of sugar, baking powder, baking soda, and salt

In a separate bowl, whisk together your milk, egg, vanilla, and melted butter

Sift your dry ingredients into your wet and mix until just combined but no longer lumpy. Pour into your prepped baking pan

To assemble, sprinkle half of the crumb mixture evenly over the top of the batter in the pan. Then, spoon your cooked strawberries in a layer over the crumbs, leaving a half-inch rim along the edge of the pan. This will help prevent your strawberries from sticking to the pan, so it’s easy to remove the coffee cake once cooled. Cover the strawberry layer with the remaining crumb topping

Bake for 60 minutes. The crumble will stay fairly white throughout the bake, but any crust that peeks through will be a deep golden brown

Cool in the pan for one hour before removing. Slice and enjoy!