Step 1: Preheat your oven to 350°F (175°C) and grease an 8×8 inch baking pan or line it with parchment paper for easy removal.
Step 2: In a small saucepan over medium heat, melt the butter. Continue cooking, whisking constantly, until the butter turns a golden brown and smells nutty. Immediately pour into a large mixing bowl.
Step 3: Add the dark brown sugar and maple syrup to the browned butter. Whisk until smooth and slightly cooled.
Step 4: Add the eggs and vanilla extract. Whisk vigorously for 1-2 minutes until the mixture is pale and shiny; this ensures a crackly top on your maple pecan blondies.
Step 5: Gently fold in the flour, salt, and baking soda with a spatula until just combined. Do not overmix.
Step 6: Stir in 1 cup of the toasted pecans. Spread the batter evenly into the prepared pan and sprinkle the remaining pecans on top.
Step 7: Bake for 22-26 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out with just a few moist crumbs. Do not overbake to keep them fudgy.
Step 8: Allow the maple pecan blondies to cool completely in the pan before slicing into 16 squares.