2 1/2 cups all-purpose flour
1/2 teaspoon baking soda
1/4 teaspoon salt
1 stick unsalted butter, at room temperature
2/3 cup packed dark brown sugar
1/2 cup pure maple syrup
1 large egg
1/2 teaspoon pure vanilla extract
1/4 teaspoon maple extract
Cooking spray
1/2 cup turbinado sugar
1/2 cup walnut halves