Preheat the oven to 350°F (175°C) and grease a loaf pan.
Whisk together the flour, granulated sugar, baking powder, cinnamon, and salt in a large bowl.
Mix the whole milk, eggs, melted butter, and vanilla until smooth in a separate bowl.
Combine the wet and dry ingredients gently, taking care not to overmix.
Prepare the cinnamon sugar topping by mixing brown sugar and cinnamon in a small bowl.
Layer the batter in the pan: pour half into the pan, sprinkle with half the cinnamon sugar, then add the remaining batter followed by the rest of the topping.
Bake for 55-60 minutes, or until golden brown and a toothpick inserted comes out clean.
Cool for a few minutes before removing it from the pan.
