For the grilled cheese soldiers: Place the Robiola in the freezer to firm up. Add enough oil to coat the bottom of a medium saucepan, add the garlic and cook over medium heat. Remove the garlic when aromatic and add the mushrooms. Saute until golden brown, remove from the heat and add the marjoram.
Preheat a griddle pan over medium heat.
Cut the Robiola into 8 slices. Butter one side of each bread slice. On each of the unbuttered sides of 4 slices place 2 Fontina slices, some of the mushrooms and 2 of the Robiola slices. Place on the griddle butter-sides down. Place the other four slices of bread on top, buttered-sides up. Flip over when the undersides of the sandwiches are golden and crispy, applying pressure with another pan or grill press. Remove from the griddle when the second sides are golden and the cheese has fully melted. Cut off the edges and slice each sandwich into two 1 1/2-inch rectangles.
For the butternut squash soup: Add enough oil to coat the bottom of a large pot and place over medium-high heat. Add the squash, potatoes, onion, apple, fennel and garlic and season with salt. Stir to coat the mixture with the oil and sweat, 5 to 6 minutes. Add the wine to deglaze the pan and cook until reduced by half.
Add the vegetable stock and season with salt and red pepper flakes. Bring to a boil, reduce to a simmer and cook until the squash is falling apart, 35 to 40 minutes. Add water if necessary to keep the squash submersed.
Puree the soup with a handheld immersion blender. If using a countertop blender, cool the mixture for about 5 minutes and carefully add it to the blender. Blend until very smooth and velvety. Check the consistency. If it is too thick add water to thin it. Season to taste, adding the sugar if needed.
Whip the cream in a large bowls until it holds its shape in soft peaks. Refrigerate until ready to use.
Ladle the soup into serving bowls and top each with a dollop of the whipped cream and some chopped Oyster Mushroom Chips. Garnish with minced chives. Serve with the grilled cheese soldiers.
Oyster Mushroom Chips:
Preheat oven to 375 degrees F.
Put the mushrooms in a large bowl and toss with olive oil until lightly coated; season with salt and red pepper. Using two baking sheets, spread the mushrooms in a single layer; you don¿t want them to overlap.
Roast the mushrooms for 10 to 12 minutes, or until brown and "cooked on" or stuck to the baking sheet. Remove from the oven and let cool for 5 minutes. Use a bench scrape to get the mushroom chips off the bottom of the baking sheet.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.