Heat the oven to 350°F. Grease an 8- x 8-inch baking pan with cooking spray and line with parchment paper, leaving overhang on two sides.
Make the maple walnuts: In a small sauté pan, heat the walnuts, 1 tablespoon maple syrup, and a pinch of salt over medium heat. Cook, tossing often, until the nuts are lightly toasted and the bottom of the pan looks dry, about 4 to 5 minutes. Transfer the walnuts to a cutting board to cool, roughly chop, and set aside.
Make the batter: In a large bowl, combine the melted butter, brown sugar, 2 tablespoons maple syrup, egg, vanilla, and bourbon (if using) and whisk until the batter is smooth. Add the flour, salt, baking powder, and nutmeg, and stir until everything is just combined.
Transfer the batter to the prepared pan and smooth with a small offset spatula. Sprinkle the walnuts evenly over the top of the batter.
Bake for 21 to 23 minutes, or until the bars are just starting to brown at the edges. They should seem slightly underbaked and will firm up as they cool.
Sprinkle the blondies lightly with sea salt flakes if you want, then allow to cool to room temperature in the pan. When the blondies are them completely cool, remove from the pan using the parchment paper and cut into squares.
You can serve the blondies at room temperature or chilled. Enjoy!
Use a robust (dark) grade of maple syrup as it’s more flavorful. I used maple syrup that was aged in bourbon barrels to intensify the bourbon influence.I like the spicy flavor of adding bourbon to the batter, but you can leave it out if you want.Make sure to underbake these blondies slightly by taking them out just before they’re fully baked. That will insure a chewy product. You can even refrigerate the blondies for optimal chewiness, and they're especially good straight from the fridge.