Broiled Fennel with Parmesan Cheese

Position rack in upper third of oven. Preheat broiler to high.

Mix oil and crushed red pepper in a small bowl. Trim stalks off fennel and discard, reserving fronds for garnish. Stand the fennel upright and cut the bulb lengthwise into 1/2-inch-thick slices. Arrange the slices in a single layer on a rimmed baking sheet. Brush with the oil mixture and sprinkle with salt. Broil until charred and tender, about 8 minutes. Sprinkle evenly with cheese. Broil until the cheese is bubbly, 1 to 2 minutes. Serve topped with chopped fronds, if desired.