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 1 cup granulated sugar, ? cup melted butter, 2 large eggs, 1 teaspoon vanilla extract, 1 teaspoon ground cinnamon, and ¼ teaspoon ground nutmeg to the bowl. Mix thoroughly with an electric mixer until smooth.
Add ¼ cup heavy cream and mix until fully combined.
Pour the mixture into the prepared casserole dish.
In a separate bowl, stir together 3 tablespoons melted butter, 1 cup brown sugar, ? cup all purpose flour, and 1 cup 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.