Adjust oven rack to middle positions and heat oven to 350°F. Spray an 8x8-inch square baking pan with nonstick cooking spray.

In a medium mixing bowl, whisk together flour, salts and baking soda.

In a heavy, large saucepan set over low heat, melt butter. Remove from heat and add brown sugar.

Cool mixture for 2 minutes and add eggs and vanilla; whisk until smooth.

Use a rubber spatula to stir in the flour mixture and half of the chocolate and the peanut butter chips. Also, add half of the peanuts, if using.

Spread batter evenly in the prepared pan and sprinkle with the remaining chips and peanuts.

Bake at 350°F for 25-35 minutes or until a toothpick inserted in the center comes out clean – the edges should just begin to pull away from the sides of the pan.

Transfer the Blondies to a cooling rack and leave in the pan to cool completely.

The Blondies can be made up to 2 days ahead. To store, cover tightly and store at room temperature.

The Blondies freeze beautifully.

Enjoy!