Heat the marinara in a large skillet over medium heat until it bubbles and is heated through.
Add the cooked fettuccine to the sauce in the skillet, using tongs to coat the pasta with the sauce.
Add desired additions.
Spoon the ricotta over the pasta, dropping it here and there, stirring gently to partially incorporate.
Remove from the heat and cover the skillet to melt the cheese for a minute or two.
Toss a salad and dinner is ready!