6 tablespoons (3/4 stick) unsalted butter, room temperature
1/2 cup nutty old-fashioned-style or freshly ground peanut butter
1 1/4 cups (packed) golden brown sugar
2 large eggs
2 teaspoons vanilla extract
3/4 cup all purpose flour
1 teaspoon baking powder
1/4 teaspoon salt
3/4 cup Ghirardelli 60% cocoa chocolate chips

1. Preheat oven to 350°F. Generously butter and flour 8-inch square baking pan.
2. Using electric mixer, beat butter in large bowl until smooth. If oil has separated from peanut butter, stir to blend. Add peanut butter to butter; beat until well blended, scraping down sides of bowl occasionally
3. Beat in brown sugar. Add eggs 1 at a time, beating well after each addition. Beat in vanilla.
4. Sift flour, baking powder and salt into medium bowl.
5. Add to peanut butter mixture; beat until blended. Stir in chocolate.
6. Transfer batter to pan. Using spatula, smooth top.
7. Bake until toothpick inserted 2 inches from edge of pan comes out with moist crumbs attached, about 40-50 minutes. Transfer pan to rack and cool completely. (Can be made 3 days ahead. Cover; store at room temperature.)

Makes 9 large square brownies.