01 - Preheat the oven to 350°F. Grease a 9×9 inch baking dish with butter or nonstick spray.
02 - In a large bowl, combine pumpkin purée, granulated sugar, eggs, whole milk, heavy cream, pumpkin pie spice, vanilla extract, and salt. Whisk until completely smooth and no lumps remain. Pour the filling evenly into the prepared baking dish.
03 - In a medium bowl, whisk together the all-purpose flour, packed light brown sugar, rolled oats, ground cinnamon, and a pinch of salt. Add the cold cubed butter and cut it in using a pastry cutter or your fingertips until the mixture resembles coarse crumbs with some pea-sized butter pieces remaining.
04 - Sprinkle the crisp topping evenly over the pumpkin filling, covering the surface completely.
05 - Bake for 40 minutes, or until the topping is golden brown and the filling is just set with a slight jiggle in the center.
06 - Allow the crisp to cool for at least 15 minutes before serving. Serve warm or at room temperature, optionally topped with whipped cream or vanilla ice cream.