Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan well, or line it with parchment paper.

In a medium bowl, whisk together flour, baking powder, and ground cinnamon.

In a separate large bowl, combine melted butter with granulated sugar and brown sugar. Whisk until smooth.

Beat in the eggs one at a time, stirring well after each addition. Then stir in whole milk and vanilla extract.

Fold the dry flour mixture into the wet ingredients until just combined.

Pour half the batter into the prepared pan and sprinkle half of the cinnamon sugar topping over it. Add the remaining batter and sprinkle with the remaining topping. Swirl gently.

Bake the loaf for 50–60 minutes or until a toothpick inserted in the center comes out clean.

Cool the loaf in the pan for 10 minutes, then transfer to a wire rack to cool completely.

For a glaze, whisk powdered sugar with milk or cream and vanilla until smooth. Drizzle over the cooled loaf.