Dice the cauliflower into even-sized florets. Add to a saucepan of boiling water. Bring to a simmer and cook for 4-5 minutes or until only just tender. Drain completely and pat dry.
Preheat the oven to 400 degrees Fahrenheit. Finely chop the rosemary and add to a small bowl along with the ground almonds, grated Parmesan, and a pinch of salt and pepper. Stir together well to combine.
Arrange the cauliflower florets in an even layer in the base of an ovenproof dish. Scatter over the dried cranberries and season with a pinch of salt and pepper. Roughly dice the butter and dot around the cauliflower.
Sprinkle the seasoned ground almond and Parmesan crumb over the top of the cauliflower and butter. Transfer to the oven and bake for 20-25 minutes. The crumb should be golden and the cauliflower tender and buttery. Serve hot alongside your Keto Thanksgiving mains.