Preheat your oven to 350°F (180°C). Line an 8×8 inch (20×20 cm) pan with parchment paper, leaving an overhang. Alternatively, you can lightly grease the pan.

Peel and core the apple, then slice it into small chunks (about 3/4 to 1 cup). Toss the apple slices with 1/2 teaspoon of cinnamon and set them aside.

In a separate bowl, whisk together the flour, the remaining 1/2 teaspoon of cinnamon, nutmeg, baking powder, and salt. Set this aside.

In a large bowl, whisk together the melted butter and light brown sugar until you can no longer see any pools of melted butter.

Add the egg and vanilla extract to the butter and sugar mixture, whisking until combined.

Stir the flour mixture into the butter mixture until there are no lumps or streaks of flour visible.

Gently fold in the cinnamon-infused apple pieces into the batter until evenly distributed.

Spoon the batter into the prepared pan and smooth it into an even layer.

Bake in the preheated oven for approximately 22-25 minutes or until the top looks set, and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Allow the blondies to cool completely. If you used parchment paper, lift them out of the pan using the overhang. If you greased the pan, slice them directly in the pan.