Preheat oven to 375°F. Butter a 12-inch cast iron skillet or a medium casserole dish. Set aside.
In a large bowl, whisk together pumpkin, sugar, eggs, pumpkin pie spice, salt, and vanilla
extract. Whisk in heavy cream until smooth. Pour into prepared skillet and set aside.
In a medium bowl, whisk together flour, sugar, cinnamon, and salt. Add melted butter and stir
with a fork until crumbly. (Can also beat with a hand mixer until crumbly if needed.)
Spread cinnamon streusel topping on top of pumpkin pie mixture in an even layer.
Bake until filling is set and top is golden brown, 40 to 45 minutes.
Let cool for 10 minutes, then serve warm topped with Vanilla Ice Cream.