Preheat your oven to 350°F (175°C) and lightly coat an 8½ x 4½-inch loaf pan with nonstick spray. In a large bowl, whisk together the flour, granulated sugar, baking powder, and salt until evenly combined.

In a separate mixing bowl, whisk the milk, egg, melted butter, and vanilla extract until smooth and fully incorporated. Pour the wet ingredients into the dry ingredients and stir gently just until combined. Avoid overmixing—the batter should be slightly runny.

Transfer the batter into the prepared loaf pan, spreading it out evenly. Bake for 60 to 70 minutes, or until the top is golden and a toothpick inserted in the center comes out with just a few moist crumbs.

Remove the bread from the oven and allow it to cool in the pan for about 10 minutes. Then, carefully take it out and place it on a large piece of parchment paper.

While the bread is still warm, brush the entire surface with the melted butter intended for the topping. In a small bowl, combine the granulated sugar, cinnamon, and nutmeg.

Sprinkle the spiced sugar mixture generously over the buttered loaf, turning the bread to coat all sides evenly. Any remaining mixture can be saved for later use.