Add the sausage meat to a Dutch oven/large soup pot. Sauté over medium-high heat, stirring occasionally, until the sausage is browned all over (about 7-8 mins.).
Remove the sausage from the pot and transfer to a paper towel lined plate. Leave about a tablespoon of the fat in the pot (drain any excess).
Add the onion and celery to the pot and cook for about 5 minutes.
Add the flour and garlic and cook for about one minute, stirring constantly.
Slowly add the chicken broth and stir until the flour has been incorporated.
Add the canned tomatoes, oregano, and crushed red pepper flakes to the pot. Also add the sausage back in. Increase the heat to high and bring the soup to a gentle boil.
Once it's boiling, add the gnocchi and cream. Reduce the heat so it's gently simmering. Cook for 10 minutes, stirring occasionally to ensure the gnocchi isn't sticking to the bottom of the pot. If needed, add another splash of chicken broth and/or cream to thin the soup out a bit more.
Stir in the spinach (if using) and season with salt & pepper to taste.
