Preheat the oven to 350 degrees Fahrenheit. Line a 9x13 pan with parchment paper, and lightly grease with nonstick spray. Set it aside.
Add the melted butter and sugars to a large bowl and mix them together. 1 cup unsalted butter, 1 1/4 cups dark brown sugar, 1/2 cup granulated
Add in the eggs, and vanilla extract and stir until completely combined. 2 large eggs, 1 TBS vanilla extract
In another medium bowl, whisk together the flour, baking powder, and salt. 2 cups flour, 3/4 tsp baking powder, 1/2 tsp salt
Gently fold the dry ingredients in with the wet ingredients, just enough to combined.
Add in the baking chips, if using them. 1 1/2 cup baking chips
Scoop batter (it is thick) into the prepared pan and spread to the edges of the pan.
Bake for 25 to 30 minutes, or until a toothpick inserted in the middle comes out clean.
Cool, before slicing into the bars and enjoying.
Store any remaining blondies in an airtight container for 2 to 3 days