Combine 2 cups blueberries, 1/3 cup granulated sugar, and 1 tablespoon lemon juice in a medium saucepan; stir cornstarch slurry into the pan and cook over medium heat until thickened, 6–8 minutes; cool to room temperature and reserve 1/3 cup for the filling.

Preheat oven to 350°F; in a bowl mix 1 1/2 cups flour, 3/4 cup oats, 1/2 cup brown sugar, 1/2 teaspoon cinnamon, and 1/4 teaspoon salt; cut in 10 tablespoons cold butter until clumpy, stir in 1 egg until combined.

Press two-thirds of crumble into the bottom and up the sides (1/2 inch) of a 9-inch springform pan and spread the remaining crumble on a parchment-lined rimmed sheet; bake both for 12–14 minutes until set and toasted; cool.

Reduce oven to 325°F; beat 24 ounces cream cheese with 2/3 cup sugar until smooth, add 1/2 cup sour cream, 1 teaspoon vanilla, and lemon zest; add eggs one at a time, mixing gently after each; stir in 2 tablespoons flour.

Fold 1/3 cup cooled blueberry compote gently into the filling to create streaks without fully blending.

Pour filling over cooled crust, drop spoonfuls of remaining compote on top and swirl lightly, then sprinkle reserved toasted crumble over the surface; place springform on a rimmed sheet pan and bake at 325°F for 50–60 minutes until edges are set and center jiggles slightly.

Turn off oven, crack door open, and let cheesecake cool inside for 1 hour; then cool on the counter 1 hour more.

Cover loosely and refrigerate at least 8 hours or overnight; run a knife around the pan before releasing the springform, top with extra compote and fresh berries if desired, and serve chilled.