In a dutch oven, over medium-high heat, saute carrots and shallots in bacon fat until tender. Stir in thyme until fragrant, then add roasted red peppers and tomatoes. Stir and cook for about 3 minutes.
Scrape everything into a blender and add 1 cup of chicken stock. Loosely fit the lid on top, allowing a way for some air to escape. Slowly start to blend and continue until all ingredients are pureed.
Scrape puree back into the dutch oven and add remaining chicken stock and bay leaf. Bring to a boil, then simmer for 10-15 minutes.
While the soup is simmering, prepare your grilled cheese. You can make this healthier by toasting the sandwich in a toaster oven without butter instead of pan frying it.
Finally, still the half and half (or sour cream) into the soup just before serving. Garnish with bacon bits.