Preheat your oven to 350 degrees Fahrenheit and grease a 12-inch cast iron skillet or a 9-inch baking dish with non-stick cooking spray.
In a large bowl combine 5 cups chopped strawberries, 1 tablespoon lemon juice, 3 tablespoons granulated sugar, and 3 tablespoons all-purpose flour. Spoon the strawberry mixture into the prepared skillet.
In a food processor, add 1 cup all-purpose flour, ¾ cup brown sugar, and 10 tablespoons unsalted butter. Pulse until the mixture is crumbly then stir in ¾ cup rolled oats.
Crumble the oat mixture on top of the strawberry mixture.
Bake for 40 to 45 minutes or until the top is golden brown and the berries are soft and bubbly.
Serve immediately with whipped cream or ice cream, if desired.
