Heat a large high-rimmed oven-safe sauté pan over medium heat. Add the Italian Sausage with the casings removed. Break the sausage into small pieces using a wooden spoon and cook for about 5 minutes.
Add the diced onion and minced garlic and cook for 5 more minutes, stirring often.
Pour in the marinara sauce and water. Stir to combine. Add the uncooked orzo and stir to combine. Season to taste with salt and pepper.
Cook over medium low heat, stirring often so the orzo doesn't stick to the bottom of the pan. Add more water if needed to cook the orzo. This should take about 12-15 minutes.
Once the orzo is mostly cooked through, dollop spoonfuls of ricotta on top. Scatter the pieces of fresh mozzarella on top as well.
Transfer to the oven to bake for 5-10 minutes until the cheese is melted. Alternatively, you could cover with a lid and leave on the stove to melt.
Divide into bowls and serve with parmesan cheese and fresh basil as desired.