2 cups all-purpose flour
3/4 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup unsalted butter, at room temperature
1 1/2 cups (packed) light brown sugar
1/2 cup sugar
2 large eggs
1 teaspoon vanilla extract
1 cup chocolate chips
1 cup butterscotch chips or Heath Toffee Bits
1 cup coarsely chopped walnuts or pecans
1 cup sweetened shredded coconut
Preheat the oven to 325 degrees F. Butter a 9×13-inch baking pan and put it on a baking sheet.
Whisk together the flour, baking powder, baking soda and salt.
Beat the butter on medium speed until smooth and creamy. Add both sugars and beat for another 3 minutes, or until well incorporated. Add the eggs one by one, beating for 1 minute after each addition, then beat in the vanilla. Reduce the mixer speed to low and add the dry ingredients, mixing just until they disappear into the batter. Using a rubber spatula, stir in the chips, nuts and coconut. Scrape the batter into the buttered pan and use the spatula to even the top as best you can.
Bake for about 40 minutes, or until a knife inserted into the center of the blondies comes out clean. The blondies should pull away from the sides of the pan a little and the top should be a nice honey brown. Transfer the pan to a rack and cool for about 15 minutes before turning the blondies out onto another rack. Invert onto a rack and cool the blondies to room temperature right side up.
Cut into 32 bars, each roughly 2-1/4 x 1-1/2 inches.