Step 1: In a large bowl, whisk together 2 ¼ cups all-purpose flour, 1 teaspoon granulated sugar, and ½ teaspoon salt.
Step 2: Add 1 cup (2 sticks) unsalted butter, very cold and cut into ½-inch cubes. Using a pastry blender or your fingertips, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces remaining.
Step 3: Gradually add ½ cup ice water, one tablespoon at a time, mixing until the dough just comes together. Be careful not to overmix.
Step 4: Form the dough into a disc, wrap it tightly in plastic wrap, and refrigerate for at least 30 minutes.
Step 5: On a lightly floured surface, roll out the chilled dough into a 12-inch circle. Carefully transfer the dough to a 9-inch pie plate. Trim and crimp the edges as desired. Prick the bottom of the crust with a fork several times. Refrigerate the pie crust while you prepare the fillings.
Step 6: In a medium bowl, beat 8 ounces full-fat cream cheese (softened to room temperature) with ½ cup granulated sugar, 1 large egg, 2 tablespoons all-purpose flour, 1 teaspoon vanilla extract, and 1 tablespoon lemon juice until smooth and creamy. Set aside.
Step 7: In another large bowl, gently combine 4 cups fresh or frozen blueberries, ½ cup granulated sugar, ¼ cup all-purpose flour, 1 teaspoon lemon zest, and ½ teaspoon ground cinnamon. Mix carefully so as not to crush the blueberries.
Step 8: In a separate bowl, combine 1 cup all-purpose flour, ½ cup packed light brown sugar, ½ cup old-fashioned rolled oats, and ½ teaspoon ground cinnamon. Add ½ cup (1 stick) cold unsalted butter, cut into small cubes.
Step 9: Use your fingertips or a pastry blender to rub the butter into the dry ingredients until a coarse, crumbly mixture forms.
Step 10: Preheat your oven to 375°F (190°C).
Step 11: Pour the cream cheese mixture into the chilled pie crust and spread it evenly.
Step 12: Spoon the blueberry mixture over the cream cheese layer.
Step 13: Evenly sprinkle the crumble topping over the blueberries.
Step 14: Bake for 50-60 minutes, or until the crumble is golden brown and the blueberry filling is bubbly. If the crust or crumble starts to brown too quickly, loosely tent the pie with aluminum foil.
Step 15: Allow the pie to cool completely on a wire rack for at least 3-4 hours before slicing and serving. This is crucial for the filling to set properly.