2 cups all-purpose flour
¾ teaspoon baking powder
½ teaspoon baking soda
½ teaspoon salt
2 sticks (8 ounces) unsalted butter, at room temperature
1½ cups light brown sugar
½ cup granulated sugar
1 teaspoon vanilla extract
1 cup semisweet or bittersweet chocolate chips (or 6 ounces chocolate, chopped)
1 cup butterscotch chips
1 cup coarsely chopped walnuts
1 cup sweetened shredded coconut
1. Center a rack in the oven and preheat the oven to 325 degrees F. Butter a 9x13-inch baking pan; set aside.
2. Whisk together the flour, baking powder, baking soda and salt.
3. With a stand or hand mixer, beat the butter on medium speed until smooth and creamy. Add both sugars and beat for another 3 minutes, 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 as you can.
4. Bake for about 40 minutes, or until a knife inserted into the center of the blondies comes out clean. The blondies should pull away fromthe sides of the pan a little and the top should be a nice honey brown. Transfer the pan to a rack and cool completely. Cut into bars; store in an airtight container at room temperature.