Batata Casserole with Pecan Coconut Topping

Name: Batata Casserole with Pecan Coconut Topping
Ingredients: 5 tablespoons unsalted butter, divided; 4 quarts water; 5 1/2 pounds batata (boniato) or other sweet potatoes; 3 large eggs; 1 (about 13-ounce) can full-fat coconut milk; 3/4 cup packed light or dark brown sugar; 1 teaspoon ground cinnamon; 1 teaspoon vanilla extract; 3/4 teaspoon kosher salt; 1/2 teaspoon ground ginger; 1/4 teaspoon ground allspice; 1 cup chopped pecans; 1/2 cup sweetened coconut flakes; 1/2 cup packed light or dark brown sugar; 1/4 cup all-purpose flour; 1/4 teaspoon kosher salt; 1/8 teaspoon ground allspice; 5 tablespoons unsalted butter