Cook the pasta shells just until al dente to prevent mushiness after baking. Use whole milk ricotta for creamier filling and drain if watery. Adding an egg helps bind the filling. Add red pepper flakes for a spicier sauce. Let baked shells rest 5-10 minutes before serving. For easy cleanup, spray baking dish with cooking spray or line with parchment paper. The dish freezes well for up to 3 months.