The ravioli will stick together and get cold after it's cooked. To avoid this: preheat oven to the lowest setting and line a rimmed baking sheet with a silicone baking mat. After each batch of boiled ravioli, simply use a slotted spoon to remove the pasta from the water and place it onto the prepared baking sheet (make sure no pasta is touching). Cover with foil that's been coated in cooking spray and place in the preheated oven. Repeat until you're ready to serve!