Place a steamer basket in a large sauce pot. Add water to just below the bottom of the basket.
Bring water to boiling on high heat. Add half of the cauliflower florets, cover and reduce heat to medium-low.
Cook cauliflower until fork tender, approximately 8-10 minutes.
Place steamed cauliflower in another large sauce pot.
Repeat steaming process for the rest of the cauliflower and parsnips. Remember to check water level between steaming processes, you may need to add more.
In a small sauce pot heat heavy cream, butter, salt and pepper on low heat.
Once butter is melted, pour over steamed cauliflower and parsnips and mash with either a hand masher or mixer. For extra creamy purée use a blender and gradually pour warm heavy cream / butter mixture while blending.
Transfer to serving dish and enjoy!