01 - Preheat the oven to 350°F. Grease a 9x9 inch baking dish with butter or non-stick spray.
02 - In a large mixing bowl, whisk together the pumpkin purée, granulated sugar, eggs, whole milk, heavy cream, pumpkin pie spice, vanilla extract, and salt until completely smooth and well combined. Pour the filling evenly into the prepared baking dish.
03 - In a medium bowl, combine 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 fingers until the mixture resembles coarse crumbs with pea-sized pieces.
04 - Sprinkle the crisp topping evenly over the pumpkin filling, covering the entire surface.
05 - Bake for 40 minutes, or until the topping is golden brown and the pumpkin 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.