Preheat oven to 350°F (175°C) and grease a 9x13 inch baking dish.
In a large mixing bowl, whisk together pumpkin puree, granulated sugar, 0.5 cup brown sugar, eggs, salt, 2 teaspoons cinnamon, ginger, and cloves until smooth.
Gradually stir in the evaporated milk until fully incorporated.
Pour the pumpkin mixture into the prepared baking dish.
In a separate medium bowl, combine all-purpose flour, rolled oats, 1 cup brown sugar, and 1 teaspoon cinnamon.
Cut the cold cubed butter into the flour mixture using a pastry cutter or fork until the mixture resembles coarse crumbs.
Stir in the chopped pecans and sprinkle the topping evenly over the pumpkin layer.
Bake for 45 to 50 minutes, or until the topping is golden brown and the pumpkin filling is set around the edges.
Remove from oven and allow to cool for at least 20 minutes to allow the custard to firm before serving.