Preheat oven to 350°F (175°C).
Grease 9x5 loaf pan thoroughly.
Mix flour, sugar, baking powder, salt together.
Combine melted butter, egg, milk, vanilla separately.
Pour wet ingredients into dry mixture slowly.
Stir until just combined, avoid overmixing.
Pour batter into prepared loaf pan evenly.
Bake for 40-45 minutes until golden.
Cool in pan for 10 minutes.
Mix cinnamon and sugar in small bowl.
Brush warm bread with melted butter completely.
Roll bread in cinnamon sugar mixture generously.