Step 1: Preheat the Oven
Preheat your oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan or line it with parchment paper for easy removal.

Step 2: Make the Batter
In a large mixing bowl, cream together the softened butter and sugar until light and fluffy. Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry ingredients to the butter mixture, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined, being careful not to overmix.

Step 3: Prepare the Cinnamon Swirl
In a small bowl, combine the sugar and ground cinnamon for the swirl.

Step 4: Assemble the Bread
Pour half of the batter into the prepared loaf pan and spread it evenly. Sprinkle the cinnamon sugar mixture evenly over the batter. Top with the remaining batter and spread it gently to cover the cinnamon layer completely.

Step 5: Bake the Bread
Bake in the preheated oven for 50-60 minutes, or until a toothpick inserted into the center comes out clean. If the top begins to brown too quickly, loosely cover the bread with aluminum foil during the last 10-15 minutes of baking.

Step 6: Add the Topping
While the bread is still warm, brush the top with melted butter. In a small bowl, mix together the granulated sugar and cinnamon for the topping, then sprinkle it generously over the buttered loaf.

Step 7: Cool and Serve
Allow the bread to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and serve as desired.