Heat oven to 350°F. Place paper baking cup in each of 18 regular-size muffin cups.
In large bowl, mix flour, cocoa, brown sugar, baking soda and salt. Add oil, water, vinegar and vanilla to flour mixture, stirring just until smooth (do not overmix).
In another large bowl, beat egg, cream cheese, peanut butter and granulated sugar with electric mixer on medium speed until smooth. Add powdered sugar; beat until creamy.
Spoon 1 level tablespoon chocolate batter into each cup; evenly spread 1 level tablespoon peanut butter filling on top. Repeat layers. Sprinkle with peanut butter chips and chocolate chips.
Bake 25 to 30 minutes or until toothpick inserted in center comes out clean (do not overbake). Cool in pan 15 minutes. Remove from pan to cooling rack; cool 15 minutes. Serve warm or cool.