Cook 2 or 3 meals at once (depending on oven size). For instance last night made barbecue pork and chicken. Be careful to put food that takes longer in first. Last week I made a stuffed chicken (make soup and sandwiches from leftovers) and lasagna (freeze extras for another meal). You could cook a roast and used left overs for sandwiches and soup.
After cooking the main meal I use leftovers to make casseroles and other meal thoughout the week.