This recipe is a great way to introduce cauliflower to someone who doesn't usually love it. Caramelization sounds fancy, but it's really a simple way to bring out the flavor of your vegetables—and it's no harder than browning steak in a pan.
Remove the green outer leaves and cut cross sections of the cauliflower into ½-inch (1¼-cm) thick slices. Remove any parts of the fibrous core of the cauliflower that remain.
Transfer the slices to a large, straight-sided skillet and add enough cold water to come halfway up the sides of the cauliflower, about ¼-inch (6mm) deep. Add the butter, sugar, and lemon juice; season with salt and pepper. Cook over high heat until the water evaporates and the cauliflower is golden brown on one side, 10–12 minutes. After the cauliflower begins to caramelize, reduce the heat to low.
Pick and slice the sage leaves. Once the cauliflower is deeply browned and the sugar has caramelized, rotate the slices to promote even browning. After a few moments, flip the cauliflower to cook the other side, about 5 minutes. Transfer to a serving dish and sprinkle with sage, hazelnuts, and freshly grated Parmesan.