Boil water in a pot, adding a good pinch of salt.
While that heats up, cook Italian sausage in a skillet over medium-high heat. Break it into bite-size pieces with a wooden spoon, cooking until fully done (about 8-10 minutes).
Add cream cheese to the sausage, let it melt, and then stir in marinara sauce. Reduce heat to medium-low.
Cook tortellini as per package instructions, then drain.
Carefully fold the cooked tortellini into the sausage ragu until well coated. Taste and adjust seasoning with salt and pepper based on your marinara sauce.
Sprinkle shredded mozzarella over the tortellini. Broil in the oven for 3-5 minutes until melted. Keep an eye on it!
Top with fresh basil and serve.