01 - Preheat the oven to 350°F. Grease a 9×9-inch baking dish with butter or nonstick 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. Pour the filling into the prepared baking dish and spread it into an even layer.
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 fingertips until the mixture resembles coarse crumbs with some pea-sized pieces remaining.
04 - Scatter the crisp topping evenly over the pumpkin filling, covering the entire surface.
05 - Bake for 40 minutes, or until the topping is deep 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 a scoop of vanilla ice cream.