Preheat your oven to 350°F (175°C) and grease an 8x8 or 9x9-inch baking dish.

In a large bowl, cream together ½ cup of softened butter and 1 cup of sugar until light and fluffy. Add 2 eggs, 1 cup of milk, and 1 teaspoon of vanilla extract, mixing well. Gradually stir in 2 cups of flour, 2 teaspoons of baking powder, and 1 teaspoon of cinnamon until just smooth.

In a small bowl, melt ¼ cup of butter and mix it with ¾ cup of sugar and 2 tablespoons of cinnamon to create the cinnamon swirl mix.

Pour half of the cake batter into the greased baking dish and dollop half of the cinnamon mixture over it. Use a knife to swirl gently. Repeat with remaining batter and cinnamon mixture.

Bake for 30-35 minutes until a toothpick comes out clean. Allow to cool for 10 minutes.

Prepare the glaze by whisking 1 cup of powdered sugar with a few tablespoons of milk until smooth, then drizzle over the warm cake.

Slice into squares and serve warm with coffee or tea.