Melt butter in a heavy pot over medium heat. Add bacon and cook until crisp and the fat is rendered off into the pan. Add chopped leeks and potatoes to the pan and cook until the leeks are soft.
Stir in white wine to deglaze the pan. Add stock, bay leaves, and thyme then season generously with salt and pepper.
Simmer until the potatoes are very soft. Remove bay leaves. Blend the soup with an immersion blender until creamy with just a few chunks. Remove from heat and cool slightly before adding the cream. Taste and season with additional salt and pepper, if needed, or a sprinkle of crushed red pepper or hot sauce, if desired.
Soup will thicken slightly as it cools.
