Step 1

Preheat the oven to 350°F. Lightly coat a 9x9-inch square pan with nonstick spray.

Step 2

In a bowl, stir together flour, baking powder, 1/2 teaspoon cinnamon and salt. Set aside.

Step 3

In a large bowl, mix together brown sugar, 1/2 cup granulated sugar, and melted butter until well blended. Stir in the egg and vanilla until smooth.

Step 4

Stir the flour mixture into the wet ingredients; the batter will be thick. Fold in the chopped apple and walnuts.

Step 5

Spread the batter into the prepared baking dish, gently pushing to the edges and corners.

Step 6

In a small bowl, stir together the remaining 2 teaspoons granulated sugar and 1/2 teaspoon ground cinnamon. Sprinkle evenly over the top of the batter.

Step 7

Bake for 25 minutes. Let cool completely, then cut into squares and serve.