Spiced Dulce de Leche Banana Bread

Name: Spiced Dulce de Leche Banana Bread
Ingredients: Cooking spray; 1 1/2 cup ( 190 g ) all-purpose flour; 1/2 teaspoon baking soda; 1/2 teaspoon kosher salt; 1/2 teaspoon ground cinnamon; 1/2 teaspoon ground nutmeg; 3/4 cup ( 150 g ) granulated sugar; 3/4 cup dulce de leche; 3 medium ripe bananas , roughly chopped; 1/3 cup ( 76 g ) unsalted butter , melted and cooled slightly; 2 large eggs; 3 tablespoons all-purpose flour; 3 tablespoons brown sugar; 1/4 teaspoon kosher salt; 2 tablespoons unsalted butter , room temperature; 1/4 cup dulce de leche, optional; About 1 tablespoon milk , optional