Cauliflower Steaks with Cannellini Mash

Heat the oven to 425°F with racks in the upper and lower thirds. Wash your hands and clean the preparation surfaces. Rinse the cauliflower, lemon, and parsley under running water, remove any damaged areas, and dry thoroughly. Drain and rinse the beans and capers. Mince the garlic, chop the parsley, and measure the lemon zest and juice.

Remove the cauliflower leaves and trim only the dry end of each stem, leaving the central core intact. Stand each head on its stem and cut it vertically through the center. Cut one 1 1/2-inch-thick steak from the central face of each half, yielding four steaks with core attached. Reserve the loose outer florets for another meal.

Arrange two steaks on each baking sheet with space between them. Rub both sides with the 2 tablespoons olive oil allocated to the cauliflower, then season both sides with its 1/2 teaspoon salt and 1/4 teaspoon pepper.

While the cauliflower roasts, heat the remaining 1 tablespoon olive oil in the saucepan over medium-low heat. Add the garlic and cook for 30–60 seconds, stirring, until fragrant but not browned. Add the beans, 1 1/4 cups water, the remaining 1/2 teaspoon salt, and the remaining 1/4 teaspoon pepper. Bring to a gentle simmer and cook for 6–8 minutes, stirring occasionally, until the beans are hot and very soft.

Remove the saucepan from the heat. Add the 2 teaspoons lemon zest and blend with an immersion blender until smooth and spoonable, keeping the blade submerged to prevent hot splashes. Cover and keep off the heat while finishing the dish. If necessary, warm briefly over low heat before serving, stirring to prevent sticking.

When the cauliflower is nearly ready, combine the capers, 3 tablespoons lemon juice, and remaining 1/4 cup water in the small skillet. Simmer over medium heat for 1 minute, then reduce the heat to its lowest setting. Whisk in the butter a few cubes at a time, adding more as each addition melts. Keep the sauce warm without letting it boil; it should be glossy and lightly thickened.

Divide the warm cannellini mash among four plates and spread it into broad beds. Place one cauliflower steak on each. Spoon all the lemon-caper butter sauce evenly over the four portions, then divide the 1/4 cup chopped parsley among them. Serve immediately.