BEAT together the butter, peanut butter, sugars and vanilla until fluffy. Beat in eggs, one at a time, until well combined. Stir in the flour.

PRESS mixture into a greased 25cm pizza pan or roll into a 25cm round and place on a greased flat tray. Bake at 180°C for 12 minutes. Sprinkle with the marshmallows and chocolate chips. Return to oven for 4-6 minutes, until lightly browned.

CUT into slices and serve with ice-cream.