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.
Right before serving, sprinkle with remaining ¼ cup Parmesan cheese and serve!
Notes
Sandy’s tips:
Choose the right sausage: Look for high-quality Italian sausage with good marbling for the best flavor. Hot or sweet Italian sausage work well.
Use freshly grated Parmesan: Pre-grated cheese doesn't melt as smoothly. Buy a block of Parmesan and grate it yourself for the creamiest texture.
Make ahead: This soup tastes even better the next day as flavors meld. Store in the refrigerator for up to 3 days.
Reheating: Reheat gently over low heat, adding a splash of broth or cream if needed to thin the soup.
Storage: Store in an airtight container in the fridge for up to 3 days. This soup also freezes well for up to 3 months (without the spinach added).
Lighten it up: Substitute half-and-half for heavy cream or use turkey sausage for a lighter version.