Can't go wrong with spaghetti and meatballs. Buy the frozen meatballs from Trader Joe's, or make and freeze your own on a free weekend. While the pasta cooks, make sauce from scratch using a 28 oz can of tomato puree (or whole tomatoes chopped up if you like the chunky texture) and some veg like onion, bell pepper, carrot, etc.
Tacos or quesadillas would also be pretty quick and easy. Brown ground beef or shred leftover roasted chicken (my preference), saute some veggies like pepper, mushroom, onion, etc. For quesadillas, I preassemble mine on a baking sheet and stick them under the broiler (watched VERY carefully) to brown them on each side. That way you can make a whole bunch at a time.
By the way, I think I'm the poster who recommended the Martha Stewart pesto pasta bake. Thanks for the reminder that I need to revisit that awesome recipe!