In a large, heavy-bottomed stock pot, over medium heat, add the olive oil, the sausage and the onion.
Saute, stirring occasionally for 30 minutes.
Remove the sausage from the pot and transfer to a paper-towel lined colander; drain excess grease.
Add the chicken stock, potatoes, rosemary and thyme to the pot.
Bring to a low boil; boil until the potatoes are just done; about 25 minutes.
Remove the thyme and rosemary sprigs.
Add the sausage and onion mixture back to the pot.
Add the heavy cream; stir well to combine.
Bring the soup back to a low boil.
Once the soup begins to bubble slightly, turn off the heat and place a lid on the pot.
Allow the soup to sit for 5 minutes.
Remove the lid; stir about a teaspoon of fresh thyme leaves into the soup and serve immediately.
Grated cheddar cheese is a great topping for this soup, optional.
