Combine cream cheese, cottage cheese and sour cream in a blender. Blend until smooth.In the bottom of your slow cooker or 9 x 13 inch pan (if you're baking in the oven), pour in half the package of tortellini.Layer half the sausage, half the sauce, all the cream cheese mixture, the rest of the tortellini, the rest of the sausage and the rest of the sauce.Sprinkle the top with Parmesan cheese.If baking in the oven, cover the pan with foil and bake for 45 minutes at 350° and then remove the foil and bake for an additional 15 minutes. If cooking in the slow cooker* cover and cook on HIGH for 3-4 hours or on LOW for 5-6 hours.Sprinkle with basil and serve.