Preheat the oven to 325 degrees Fahrenheit and spray a 1 ½ quart casserole dish with non-stick cooking spray.
Cook, peel, and mash enough sweet potatoes to make 3 cups. Place them in a large mixing bowl and allow them to cool.
Add granulated sugar, melted butter, large eggs, vanilla extract, ground cinnamon, and ground nutmeg to the bowl. Mix thoroughly with an electric mixer until smooth.
Add heavy cream and mix until fully combined.
Pour the mixture into the prepared casserole dish.
In a separate bowl, stir together melted butter, brown sugar, all purpose flour, and chopped pecans.
Sprinkle the topping mixture evenly over the sweet potato mixture.
Bake for 25-30 minutes until the center is set.
Remove from the oven and let rest for 10 minutes before serving.
Notes
Refrigerate the leftovers in an airtight container for up to 4-5 days.