Preheat the oven to 350°F (175°C) and grease a loaf pan.

In a mixing bowl, whisk together the flour, sugar, baking powder, cinnamon, and salt.

In another bowl, mix the milk, eggs, and melted butter until well combined.

Pour the wet ingredients into the dry mixture and fold gently until just mixed.

Combine 1/4 cup of sugar with 2 tsp of cinnamon for the filling.

Pour half of the batter into the loaf pan, sprinkle half of the cinnamon-sugar mixture over it, add the remaining batter, and top with the rest of the cinnamon-sugar mix. Swirl gently with a knife.

Bake for 50-60 minutes or until a toothpick comes out clean.