Informal of or characteristic of certain values, as wholesomeness or decency, esp. when regarded as being particularly American
See apple-pie in American Heritage Dictionary 4
Perfect; exemplary: put the room in apple-pie order.
often apple pie Of, relating to, or marked by values regarded as distinctively American: “Family, neighborhood, community are apple pie virtues, unassailable and unavoidable in political rhetoric”(Ronald Brownstein).