Step 1: Preheat your oven to 375°F (190°C) and grease a 9x13 inch baking dish.
Step 2: Boil the sweet potato cubes in a large pot of water until tender, about 15 minutes. Drain well.
Step 3: In a large bowl, mash the cooked sweet potatoes with melted butter, brown sugar, heavy cream, vanilla, cinnamon, and nutmeg until smooth.
Step 4: Spread the sweet potato mixture evenly into the bottom of the prepared baking dish.
Step 5: In a separate bowl, whisk together the flour, granulated sugar, and baking powder. Cut in the cold cubed butter using a pastry cutter until the mixture resembles coarse crumbs.
Step 6: Stir in the chopped pecans and maple syrup into the flour mixture until a shaggy dough forms.
Step 7: Drop spoonfuls of the dough over the sweet potato filling, covering as much surface as possible.
Step 8: Bake for 40-45 minutes, or until the topping is golden brown and the sweet potato filling is bubbling.