3 tablespoons extra virgin olive oil (EVOO)
1 1/4 pounds large celeriac (celery root), peeled and chopped
2 parsnips, peeled and chopped
1 Idaho potato, peeled and chopped
1 onion, chopped
Kosher salt and freshly ground pepper
1 bay leaf
2 tablespoons chopped fresh thyme
3 large Gala or other crispy, sweet apples, 2 peeled and chopped, 1 sliced
Juice of 1/2 lemon
1/2 cup Calvados apple liquor or 1/2 cup Sauterne (citrusy) wine
4 cups chicken stock, homemade or store-bought (32 ounces)
1 cup heavy cream or creme fraiche
1 stick butter, softened
8 1/2-inch-thick slices good-quality white bread
1/2 cup apple butter
1/3 cup honey
1/4 cup grainy Dijon mustard
3/4 pound super sharp white cheddar cheese, sliced
12 slices good-quality smoky bacon
For the soup, heat the EVOO, three turns of the pan, in a soup pot or large Dutch oven. Add the chopped celeriac, parsnips, potato, onion, bay leaf and thyme. Season with salt and pepper and cook, partially covered, to soften, 10-12 minutes, stirring occasionally. Add the apples and lemon juice and cook for 5 minutes more. Deglaze the pan with the Calvados or Sauterne and add the chicken stock. Simmer over medium-low heat, 20-25 minutes more. Then remove the bay leaf and puree the soup. If too thick, add 1 cup water to puree. Add the cream or creme fraiche, turn off the heat, cool and store for a make-ahead meal.
Butter one side of each slice of bread. Combine the apple butter, honey and mustard and spread over opposite sides of the bread. With the buttered-side facing out, build the cheese sandwiches and individually wrap for make-ahead.
To serve, pre-heat the oven to 375º F. Heat the soup up over medium heat, stirring occasionally. Arrange the bacon on a slotted pan and bake until crisp, about 15 minutes. Place the bacon and sliced apples in the prepared sandwiches. Heat a griddle pan over medium heat and make the grilled cheeses, cooking until deeply golden and crisp on both sides.