In a large mixing bowl, combine the flour, salt, baking soda, and baking powder.
In a separate large mixing bowl, beat the butter, brown sugar, and granulated sugar until fluffy.
Mix in the eggs one at a time, then stir in the vanilla extract.
Gradually mix in the flour mixture by hand until just combined (to avoid a cake-like consistency).
Fold in the chocolate chips.
Spread the batter evenly into the prepared pan and smooth the top.
Bake for 25-35 minutes, or until the center is set. If the center is still jiggly after 25 minutes, continue baking, checking every 5 minutes.
Cool in the pan for 15 to 20 minutes before slicing and serving.
Notes
If you're short on time, melt the butter and mix it into the sugars before adding the flour. The result will be a soft, chewy texture.
Mix the flour in by hand. Over-mixing can cause the blondies to come out cakey instead of gooey and dense as they should be.
The key to making blondies chewy and fudgyis not to overcook them. I bake them for 25 minutes, and to check if they’re perfectly baked, I gently shake the pan. If they jiggle, put them back in the oven for five minutes until just set (they can still have a very slight jiggle). Keeping them from being overbaked keeps the blondies perfectly moist.