For the soup, heat the EVOO, 3 turns of the pan, in a soup pot or large Dutch oven. Add the chopped celeriac, parsnips, potato, onion, bay and thyme. Season with salt and pepper and cook, partially covered, to soften, 10 to 12 minutes, stirring occasionally. Add the apples and lemon juice and cook 5 minutes more. Then deglaze the pan with the Calvados or Sauterne and add the chicken stock. Simmer over medium-low heat, 20 to 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, preheat the oven to 375 degrees 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.