1. Preheat your oven to 325°F (160°C). Grease a 9-inch springform pan lightly or line it with parchment paper.

2. In a medium bowl, mix the graham cracker crumbs and sugar. Stir in melted butter until the mixture resembles wet sand. Press evenly into the bottom of the prepared pan to form the crust. Set aside.

3. In a large mixing bowl, beat the cream cheese and sugar together until smooth and fluffy. Mix in the vanilla extract, followed by the eggs, one at a time. Ensure each egg is fully incorporated before adding the next. Stir in the sour cream until the filling is smooth.

4. Pour the cheesecake filling over the crust in the springform pan and spread evenly with a spatula. Bake in the preheated oven for 50-60 minutes, or until the center is set but still slightly jiggly. Once baked, remove from oven and let it cool completely.

5. While the cheesecake is cooling, start preparing the strawberry topping. In a medium saucepan, combine the sliced strawberries, sugar, and lemon juice. Cook over medium heat until the mixture starts to simmer. Stir occasionally to prevent sticking.

6. Dissolve the cornstarch in a tablespoon of water and add it to the simmering strawberry mixture. Cook for another 2-3 minutes until it thickens. Remove from heat and let it cool.

7. For the crumble topping, combine flour, brown sugar, melted butter, and rolled oats in a bowl. Mix until crumbly; set aside.

8. Once the cheesecake and strawberry topping have cooled, gently spread the strawberry mixture over the cheesecake.

9. Sprinkle the crumble topping evenly over the strawberries.

10. Refrigerate the assembled cheesecake for at least 4 hours or overnight to allow the flavors to meld and the cheesecake to firm up.

11. Once set, carefully remove from the springform pan, slice and serve your delightful Strawberry Crumble Cheesecake.