Fill a large saucepan with water and place over high heat.
Cut the potatoes into 1-inch chunks. Once the water is boiling, add the potatoes and cook for 8 minutes, uncovered. While the potatoes are cooking, remove the cauliflower leaves and chop into bite-size florets. When the 8 minutes is up, add the cauliflower to the boiling water and cook for another 8 minutes, uncovered, until they are fork- tender.
Drain the potatoes and cauliflower and return them to the saucepan. Add the ghee, salt, pepper and garlic and mash the mixture with a potato masher until smooth.
If you prefer a very smooth and silky consistency, use a handheld blender after you have mashed them down. If the mixture is dry (the cauliflower will release water as it’s mashed so give it a little time), add 1⁄4 cup of full-fat coconut milk and continue to mash until well incorporated.