Preheat the oven to 425 degrees. Trim the cauliflower on the bottom by removing the leaves and cutting the stem so it sits flat.
Take a large pot and add 1 inch of water to the bottom. Bring it to a boil and add the cauliflower to the pot (on a steamer basket or not) with the stem side down. Cover pot, reduce heat to low and steam for 12-15 minutes until the stem of cauliflower can easily be pierced with a knife. It should not be falling apart, just tender.
Meanwhile, make the spread. In a bowl, mix together the mayonnaise, almonds, parsley, salt and lemon. Set aside.
When cauliflower is done, set aside to cool for about 15-20 minutes. Once cool, flip cauliflower over and begin to spread the mayonnaise mixture on the bottom and inside as much as possible. Spread the remaining amount on top and all around the cauliflower. Place in a baking dish or cast iron skillet and bake for 15 minutes until lightly browned on top. Sprinkle with parsley and serve immediately!