1Heat oven to 350°F (if using dark or nonstick pan, heat oven to 325°F). Grease bottom and sides of 15x10x1-inch pan with shortening or spray with cooking spray.
2In large bowl, beat sugar, butter, 2 eggs, 1 teaspoon vanilla, the flour, cocoa, oats and baking powder with electric mixer on medium speed until well mixed. Stir in peanuts. In small bowl, reserve 1 1/2 cups oat mixture for topping. Press remaining oat mixture on bottom of pan to form crust.
3In medium bowl, beat cream cheese on medium speed until smooth. Add 3 eggs, the milk, peanut butter and 1 teaspoon vanilla. Beat on medium speed, scraping bowl occasionally, until well mixed. Spoon peanut butter mixture over oat mixture in pan; spread evenly to edges of pan. Carefully crumble reserved oat mixture evenly over peanut butter layer.
4Bake 35 to 45 minutes or until toothpick comes out clean. Cool completely in pan on wire rack, about 30 minutes. For bars, cut into 8 rows by 6 rows. Store covered in refrigerator.