Eat this cauliflower filet with a steak knife; it's surprisingly hefty. More Amazing Vegetarian Dishes
Preheat the oven to 375°. Cut three 3/4-inch-thick center slices from each head of cauliflower to form "steaks." Reserve the remaining cauliflower for another use.
In a saucepan of boiling salted water, cook the corn until tender, about 3 minutes. Drain and cool, then cut the kernels from the cobs.
In a medium skillet, heat 2 tablespoons of the oil. Add the chile and cook over moderately high heat for 30 seconds. Add the scallions and cook until softened, about 1 minute. Stir in the corn and capers and season with salt and black pepper.
In a large, nonstick skillet, heat 1 tablespoon of the oil until shimmering. Add 3 cauliflower steaks and season with salt. Cook over moderate heat until lightly browned, about 3 minutes per side; transfer to a large rimmed baking sheet. Repeat with the remaining 1 tablespoon of oil and 3 cauliflower steaks.
Press the corn-scallion mixture into the spaces between the cauliflower florets. Bake the cauliflower steaks for 25 minutes, until tender and richly browned.