Preheat the oven to 350°F (175°C). Grease a 9x5-inch loaf pan.
In a large bowl, whisk together the flour, sugar, baking powder, salt, and cinnamon.
In another bowl, mix the melted butter, milk, eggs, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
While the bread is baking, prepare the topping by mixing the sugar and cinnamon in a small bowl.
Once the bread is done, remove it from the oven and let it cool in the pan for 10 minutes.
Turn the bread out onto a wire rack. Brush the top and sides with melted butter, then sprinkle the cinnamon sugar mixture generously over the entire loaf.
Allow the bread to cool completely before slicing.