Cheese, Potatoes, and Mustard Dish

Roast the potatoes: Preheat oven to 450°F (230°C). Slice potatoes in half and toss with olive oil, salt, pepper, and herbs if using. Spread cut-side down on a parchment-lined baking sheet. Roast 35–40 minutes until deeply golden and crisp. Make the fontina fonduta: In a small saucepan, heat milk and butter over low until just warm. In a separate bowl, whisk egg yolk, then slowly stream in a few tablespoons of the warm milk to temper. Return mixture to the pan and stir constantly until slightly thickened (do not boil). Lower heat and add fontina, stirring until melted and smooth. Season with nutmeg and a pinch of salt. Keep warm over very low heat. Make the vinaigrette: Whisk together mustard, vinegar, and honey. Slowly drizzle in olive oil while whisking until emulsified. Season with salt and pepper. Assemble: Spoon a generous layer of warm fonduta onto a platter. Pile crispy potatoes on top, drizzle with the mustard vinaigrette, and finish with flaky salt and fresh herbs.