Ready to dive into making these delicious bars? Follow these steps, and you’ll have a batch ready in no time:

1. Preheat your oven to 350°F (175°C). Grease an 8×8-inch baking pan or line it with parchment paper for easy removal.
2. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
3. In a large bowl, combine the melted butter and brown sugar, stirring until well mixed. Add the egg and vanilla extract, and stir until smooth.
4. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix!
5. Fold in the chopped apples and walnuts, if using. The batter will be thick, but that’s exactly what you want.
6. Spread the batter evenly into the prepared baking pan. Smooth the top with a spatula.
7. Bake for 25-30 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.
8. Allow the blondie bars to cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely.

One little tip: If you can resist, let these bars cool completely before cutting. It makes slicing them so much easier and gives the flavors time to meld beautifully.