In a large mixing bowl, blend 1 ½ cups of all-purpose flour, ½ cup cold unsalted butter, and ¼ cup sugar by cutting the butter into the dry ingredients until the mixture resembles coarse crumbs. Gradually add ice water, stirring until the dough comes together. Chill in the refrigerator for 30 minutes while you preheat the oven.

Once chilled, roll out the dough on a floured surface to fit your pie dish. Carefully transfer it to the dish, trimming any excess. To prevent bubbling, prick the bottom with a fork and place parchment paper with pie weights atop. Blind bake in a preheated oven at 350°F (175°C) for 15-20 minutes, or until lightly golden.

In a large bowl, combine 1 cup pumpkin puree, 1 can sweetened condensed milk, and 1 teaspoon each of cinnamon, nutmeg, and ginger. Whisk the mixture until perfectly smooth and creamy.

Remove your pre-baked crust from the oven and let it cool slightly. Pour the pumpkin filling evenly into the crust.

In a medium bowl, mix ½ cup brown sugar, ½ cup oats, and ¼ cup cold butter, cutting the butter in until you achieve a crumbly texture. Add 1 teaspoon of cinnamon. Evenly sprinkle this crumble topping over the pumpkin filling.

Return the assembled Pumpkin Pie Crumble to the oven and bake for 25-30 minutes or until the filling is set and the topping is golden brown.

Remove the pie from the oven and allow it to cool for at least 15 minutes before serving.