01 -
Preheat the oven to 400°F.
02 -
Turn the cauliflower upside down on a cutting board. Cut off and discard most but not all of the stems, then cut the florets into small, 1/2-inch clusters. Place the florets on a sheet pan, toss them with the olive oil, red pepper flakes, 1 teaspoon salt, and 1/2 teaspoon black pepper, and spread them out in a single layer.
03 -
Roast the cauliflower florets for 25 to 30 minutes, tossing two or three times, until they are tender and randomly browned. Set aside to cool for 10 minutes.
04 -
Set the oven to broil and arrange a rack 6 inches below the heat source.
05 -
Transfer the cooled florets to a large mixing bowl. Stir in the mascarpone until the florets are evenly coated. Add the Gruyère, prosciutto, nutmeg, 1 teaspoon salt, and 1/2 teaspoon black pepper, mixing thoroughly.
06 -
Toast the bread slices in a toaster until lightly browned. Arrange them in a single layer on a sheet pan lined with foil.
07 -
Mound the cauliflower mixture evenly on each toast. Dust with paprika.
08 -
Place the toasts under the broiler and cook for 2 to 4 minutes, until browned and bubbling. Watch carefully to avoid burning.
09 -
Transfer the toasts to plates. Sprinkle with grated Parmesan, minced chives, and flaked sea salt. Serve hot.