Set pressure cooker to "brown"/"sauté" function.
Add the olive oil and let it heat up.
Add the sausage, beef, and onion, and cook, breaking up the meat with a wooden spoon, until onions are translucent and meat is browned.
Add garlic, Italian seasoning, balsamic vinegar, salt, pepper, marinara, diced tomatoes, broth, and lasagna noodles, stirring well to combine.
Place lid on the pressure cooker and make sure valve is closed.
Cook on high for 7 minutes.
Let the pressure naturally release for 10 minutes, and then release the valve completely. At this point, most of the pressure should be released so you won't have a big rush of air and moisture.
Stir in milk/cream.
While the soup is cooking, you can make the ricotta topping.
In a medium bowl, stir together ricotta, basil, cheese, and salt. I like to use a fork/whisk so it gets light and fluffy.
To serve, ladle the soup into bowls.
Top each bowl with a generous dollop of ricotta and a sprinkle of shredded Italian cheese.