Swiss centre half Schär's close range double put Eddie Howe's side in control at Villa Park before Alex Moreno's own goal extended their advantage after the break.
Ollie Watkins pulled one back for the hosts but this was a comfortable triumph for Howe's men, who eased past Unai Emery's charges to record a second win in the space of four days, following Saturday's 2-0 FA Cup win at Fulham.
Serena Taylor was at Villa Park to capture the best of the action for this nufc.co.uk gallery.