Step 1: Preheat your oven to 350°F (175°C) and grease and flour a 9x5 inch loaf pan, or line with parchment paper.
Step 2: In a large bowl, whisk together the all-purpose flour, baking powder, salt, and ½ cup granulated sugar.
Step 3: In a separate medium bowl, whisk the egg, ½ cup milk, ¼ cup melted butter, and vanilla extract until well combined.
Step 4: Pour the wet ingredients into the dry ingredients. Mix with a spoon or spatula until just combined. Be careful not to overmix; a few lumps are okay.
Step 5: Pour the batter into the prepared loaf pan and spread evenly.
Step 6: Bake for 40-45 minutes, or until a wooden skewer or toothpick inserted into the center comes out clean.
Step 7: While the bread is baking, prepare the cinnamon sugar topping. In a small bowl, melt ¼ cup unsalted butter. In another small bowl, combine ½ cup granulated sugar and 1 teaspoon ground cinnamon.
Step 8: Once the bread is out of the oven, immediately brush the top with the melted butter.
Step 9: Generously sprinkle the cinnamon sugar mixture over the warm, buttered bread.
Step 10: Let the sweet bread cool in the pan for about 10-15 minutes before transferring it to a wire rack to cool completely, or serve warm.