For The Best Texture In Ravioli, Cook Your Meat Fillings First - Tasting Table

"I always use braised beef or veal for my filling ... that's already been prepared so it really never needs to be cooked any longer than the pasta itself being boiled."

"A deeper flavor will make a tastier filling. More to Mirabile's point, a precooked filling makes it easier to cook the whole ravioli [because] you're just cooking the pasta only."

Read at Tasting Table