Prepare the potatoes: Bring a large pot of water to boil. Peel and chop potatoes into medium cubes and place in pot once water is boiling. Reduce heat to low-medium and allow potatoes to simmer for about 12-15 minutes, or until tender. Drain pot and allow potatoes to sit for 2-3 minutes.

Meanwhile, prepare the cauliflower: Preheat oven to 375ºF and line baking sheet with parchment paper or foil. Cut head of cauliflower in half and then chop into medium-large florets, measuring out about 4 cups. Place cauliflower florets and garlic cloves on lined baking sheet and drizzle with olive oil; use hands to fully coat. Roast for about 15-20 minutes, until lightly golden. Once cauliflower is cooked, transfer to food processor with S-blade, pulse a few times then add 1 tablespoon butter and 2 tablespoons yogurt. Pulse again and scrape down sides of the bowl as necessary. Cauliflower should be broken down into very tiny bits.

Make mashed cauliflower potatoes: Add drained potatoes to large bowl with cauliflower bits, remaining butter and salt; begin mixing on low speed, or use potato masher. Add in milk slowly, 1-2 tablespoons at a time while you continue to mash or mix on low speed. Only use as much milk as needed for desired consistency – I used 5 tablespoons. Taste test and add more salt if desired; mix in fresh chives.

Transfer cauliflower mashed potatoes to serving dish, garnish with more chives and slice of butter if desired. Best enjoyed warm!