1. Preheat oven to 350°F and grease a 9×13-inch baking dish. In a large bowl, whisk together pumpkin puree, evaporated milk, eggs, brown sugar, granulated sugar, cinnamon, nutmeg, ginger, cloves, salt, and 1/4 cup flour. Pour the pumpkin mixture into the prepared baking dish and smooth the top. In another bowl, combine 3/4 cup flour, oats, brown sugar, cinnamon, and salt. Cut in cold butter until the topping forms coarse crumbs. Sprinkle topping over the pumpkin filling evenly without pressing it down. Bake for 45–50 minutes, until the topping is golden and the filling is set. Cool for at least 15 minutes before serving. Serve warm with vanilla ice cream if desired.