Preheat your oven to 350°F (175°C) and line an 8x8 inch pan with parchment paper, allowing it to hang over the edges.

In a large mixing bowl, melt 1 cup of unsalted butter and stir in 1 cup of light brown sugar and 1 cup of granulated white sugar until creamy. Add 2 eggs one at a time, beating until smooth.

Gradually sift in 2 cups of all-purpose flour, 1 teaspoon of baking powder, and 1 tablespoon of cinnamon. Stir gently until just combined.

Pour half of the blondie batter into the prepared pan. Sprinkle with cinnamon sugar, then add the remaining batter and swirl together.

Bake for 30 to 38 minutes, checking for golden edges and a slightly underdone center.

Let the blondies cool in the pan for about 15 minutes before transferring to a wire rack to cool completely.

In a bowl, mix 2 cups of powdered sugar, cream cheese, and a splash of milk until smooth to prepare the frosting.

Drizzle the cream cheese frosting over the cooled blondies and slice into squares.