3 tbsp. olive oil
1 bulb fennel—trimmed, quartered, and cored, then very thinly sliced
1 large onion, quartered and thinly sliced
2 large cloves garlic, thinly sliced
Salt and pepper
1 chunk of Parmigiano-Reggiano rind (optional) if you have one in the fridge or freezer)
1 large head escarole, cut into 1/2-inch-wide ribbons
Freshly grated nutmeg, about 1/8 tsp.
2 qt. chicken stock
1 lemon, juiced (about 1/4 cup)
½ cup chopped hazelnuts or pine nuts
1 tsp. mild honey (such as acacia)
2 fat handfuls of baby arugula
1 tbsp. fresh lemon juice EVOO, for drizzling
Kosher salt or flaky sea salt
8 slices of white peasant or Italian bread (1/4 inch thick)
12 oz. Taleggio cheese, rind trimmed and cheese sliced
For the soup, in a soup pot or Dutch oven, heat the oil, three turns of the pan, over medium to medium-high. Add the fennel, onion, and garlic; season with salt and pepper. Add the Parm rind, if using. Cover and cook, stirring occasionally, until the vegetables soften, 10 to 12 minutes. Add the escarole; season with a little nutmeg. Add the stock. Bring to a boil. Reduce heat to medium. Cook at a low boil until the flavors meld, about 10 minutes.
Discard the rind and add the lemon juice just before serving.
For the panini, in a small skillet over medium heat, or in a toaster oven, toast the nuts, stirring often, until golden and fragrant, 4 to 5 minutes. Drizzle with the honey. Toss until coated. In a medium bowl, toss the arugula, lemon juice, and a drizzle of EVOO; season with kosher salt and pepper.
Heat a sandwich press to 400° or high, or heat a cast-iron or stainless-steel skillet over high. Build the sandwiches with the bread, cheese, nuts, and greens. If using a sandwich press, cook the sandwiches until the bread is golden or grill marks form and the cheese melts, about 3 minutes. If using a skillet, place a second heavy skillet on top of the sandwiches, or press down on the sandwiches with a spatula and turn over halfway through cooking. Cut the sandwiches in half. Serve with the soup.