Preheat oven to 425°F. Line a 15x10-inch baking pan with parchment paper.
Place cauliflower in prepared pan. Drizzle with 1 Tbsp. of the oil. Sprinkle with salt and cayenne pepper; toss to coat.
Remove ½ tsp. zest from the lemon. Cut lemon in half; place one half in the pan with cauliflower, cut side down. (Reserve remaining lemon half for another use.)
Roast 15 minutes.
Use the bottom of a heavy glass or measuring cup to smash cauliflower, without breaking florets, to about ½-inch thickness.
Drizzle with remaining 1 Tbsp. oil. Sprinkle with cheese.
Roast until edges of cauliflower are lightly browned, about 10 minutes more.
Squeeze roasted lemon over cauliflower and sprinkle with lemon zest and almonds.
