Brownies With Peanut Butter Chips
["1 1/4 c. butter or margarine", "1 3/4 c. sugar", "4 eggs", "2 tsp. vanilla extract", "1 2/3 c. all-purpose flour", "2/3 c. cocoa", "1/2 tsp. baking powder", "1/2 tsp. salt", "1 2/3 c. (10 oz. pkg.) Reese's peanut butter chips, divided"]
["Heat oven to 350\u00b0.", "Grease 13 x 9-inch baking pan."]
["butter", "sugar", "eggs", "vanilla extract", "all-purpose", "cocoa", "baking powder", "salt", "butter chips"]