Preheat the oven to 350 degrees . Grease an 8-inch-square glass baking dish.
Pierce the sweet potatoes once or twice with a fork; microwave on high 3 minutes. Turn them over; microwave until tender, about 2 minutes more. Let cool, then peel. In a large bowl, mash until smooth. Stir in the eggs, melted butter, cream, 2 tbsp. sugar, vanilla, cinnamon and 1/4 tsp. salt; transfer to the prepared baking dish.
In a medium bowl, combine the pecans, 3/4 cup sugar, the softened butter and the flour. Using your fingertips, blend until the nuts are coated. Sprinkle the mixture over the casserole. Bake until the center is set and the topping is lightly browned, about 30 minutes.