Preparation

• Position a rack in the center of the oven and heat to 350°F. Line a large rimmed baking sheet with a clean kitchen towel.
• In a 2-quart saucepan, bring the cream and 1 tsp. of the thyme to a simmer over medium heat. Reduce the heat to low, and cook until reduced to about 1/3 cup, 7 to 9 minutes.
• In a wide pot fitted with a steamer basket, bring about 2 inches of water to a boil. Add the cauliflower and season with 1/2 tsp. salt. Cover and steam until just tender, 8 to 10 minutes.
• Transfer the cauliflower to the prepared baking sheet and let dry for a few minutes. Remove the towel, letting the cauliflower fall onto the baking sheet, and bake the cauliflower until dry but not browned, 10 to 15 minutes. Transfer to a blender, and add the cream, lemon juice, 1/2 tsp. salt, and the cayenne. Blend until smooth. Season to taste with salt, lemon juice, and cayenne. Keep warm.
• Heat 2 Tbs. of the oil in a medium skillet over medium-high heat. Add the capers and the remaining 1/2 tsp. thyme, cover with a splatter shield (if you have one), and cook, stirring occasionally, until the capers are golden and puffed, 2 to 3 minutes. Add the lemon zest, cook for just a few seconds, and then, using a slotted spoon, transfer the capers, thyme, and zest to a paper-towel-lined plate.
• Pat the scallops dry. Heat a large cast-iron or other heavy-duty skillet over medium-high heat until very hot. Add the remaining 1 Tbs. oil and the butter. Season the scallops with salt. Working in batches if necessary to keep from crowding, cook the scallops, undisturbed, until very well browned on one side, 2 to 3 minutes. Flip and cook until just barely cooked through, 2 to 4 minutes more, depending on size. Transfer to a plate. Repeat, if necessary, wiping out the pan and adding more butter and oil as needed.
• Divide the cauliflower purée among serving plates, and top with the scallops. Garnish with the capers and parsley, and serve.