Place the cauliflower, cream and butter in a medium pot over medium heat. Cook for 12 to 15 minutes, until the cauliflower is soft.
Working in batches, if needed, puree the cauliflower in a blender with the warm cream and butter mixture; season to taste and transfer to a large bowl and set aside.
Cut the potatoes into chunks. In a large pot with a steamer basket insert, add enough water so that it comes up about 1" in the pot, but does not come into the steamer basket. Add the potato chunks and steam over medium heat for about 20 minutes. Remove from heat.
Carefully remove the steamer basket from the pot; discard any remaining liquid. Place the potatoes into a mixing bowl; using a mixer with paddle attachment, or by hand, mash potatoes until smooth.
Add 2 cups of the cauliflower puree to the mashed potatoes; season to taste with salt and pepper and mix well to combine. Garnish with Italian parsley and roasted cauliflower if desired. Wow your family and friends — serve this trendy and delicious side dish with Chef Elden’s Mongolian Lamb Chops!