Pasta casseroles are perhaps the ultimate combination of weeknight convenience and homey comfort food. Casseroles like this one don't take long to cook, and they can be put together the day before and baked or warmed up at the end of a long day. And yet these pasta bakes are comforting and delicious. This one has a double dose of spinach, spoonfuls of pesto, and, yes, plenty of cheese. It's a whole meal in one dish.