In a large dutch oven, heat olive oil over medium heat, adding the Italian sausage. Crumble the sausage with a wooden spoon, and cook until browned.

Add the chopped onion and minced garlic and continue to cook until the onion is translucent, about 3-4 minutes.

Next, add the sliced mushrooms and cook for another 4 minutes.

Add the chicken broth, diced tomatoes, and Italian seasoning. Bring to a simmer and cook for 10 minutes. Season to taste with salt and pepper.

Reduce the heat to low and stir in the heavy whipping cream and grated 1 ¼ cups Parmesan cheese. Cook until the cheese is melted and the soup is creamy.

Last step: Add the baby spinach and cook until wilted, about 2 minutes.