La Madeleine Country Potato Soup

1/8 cup unsalted butter
3 cups thinly sliced leeks
1 cup sliced yellow onion
salt to taste
1 1/2 quarts chicken broth
2 pounds russet potatoes peeled and sliced 1/4 inch thick
2 sprigs fresh thyme
1/2 cup heavy cream
1 cup grated cheddar cheese
1/2 cup bacon cooked and diced

Place the butter, leeks, and onions in a large saucepan over medium heat. Add a pinch of salt and sauté until the onions become translucent and the leeks change color.
Add the broth, potatoes, fresh thyme, and salt to taste. Cook for 40 minutes over medium heat, stirring frequently to avoid scorching.
Puree the soup with an immersion blender or in a standard blender.
Add cream and bring to a boil.
Serve hot, garnished with cheddar cheese and diced bacon.