Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the pumpkin puree, brown sugar, eggs, vanilla extract, cinnamon, and heavy cream. Whisk together until smooth.
Pour the pumpkin filling into a greased 9×13 inch baking dish, spreading it evenly.
In a separate bowl, combine the chopped pecans, oats, and melted butter. Mix until crumbly.
Evenly spread the pecan crumble over the pumpkin filling.
Place the baking dish in the preheated oven and bake for 40-45 minutes until golden.
Let cool for at least 10 minutes before serving.
Serve warm with whipped cream or ice cream.