Preheat your oven to 350 degrees Fahrenheit. Lightly grease a standard 9x5 inch loaf pan. Line the pan with a strip of parchment paper, leaving a little overhang on the sides.

In a large mixing bowl, sift together the flour, 1 cup of sugar, baking powder, and salt.

In a separate medium bowl, whisk together the melted butter, milk, egg, and vanilla extract. The mixture should be smooth and golden.

Gently fold the wet ingredients into the dry ingredients using a spatula. Stop as soon as the flour streaks disappear.

In a small bowl, mix 1/4 cup of sugar with 1 tablespoon of cinnamon. Pour about half of the batter into the prepared loaf pan. Sprinkle half of the cinnamon sugar mixture over the batter. Add the remaining batter, and top with the rest of the cinnamon sugar. Use a butter knife to gently swirl through the batter to create beautiful ribbons.

Place the pan in the center of the oven and bake for 45 to 55 minutes. You will know it is done when a toothpick inserted into the center comes out clean or with just a few moist crumbs.

Let the bread cool in the pan for about 10 minutes. While it is still warm, brush the top with a little extra melted butter and dip it into more cinnamon sugar for that authentic donut texture.