Add a few inches of water to a large pot then place a steamer basket inside. Turn the heat to high to bring the water to a boil.

Once the water is boiling, place the chopped potatoes into the steamer basket then spread into an even layer. Place a lid on top, turn the heat down to medium-low, then steam for 5 minutes.

Add the cauliflower florets on top of the potatoes then place the lid back on top and steam for another 15-20 minutes, or until the potatoes and cauliflower are tender.

Meanwhile, add 1/3 cup milk, the butter, and smashed garlic cloves to a small saucepan over low heat. Once the butter has melted, cover the pan with a lid and keep warm.

Use a large cooking spoon to transfer the steamed cauliflower into a large food processor fitted with an S-blade. It’s ok if some of the potato pieces come with the cauliflower — you don't have to be 100% precise! Remove the smashed garlic cloves from the saucepan then add half the warm milk and butter into the food processor.

Process until the cauliflower is extremely smooth and silky, 1 minute, scraping down the sides of the bowl once. Tip: remove the chute from the food processor lid to allow steam to escape while processing the hot vegetables.

Add the potatoes, salt, pepper, and remaining milk and butter then pulse to incorporate the potatoes into the whipped cauliflower. Process until the potatoes are smooth, 30 seconds or so, then taste and add more salt and pepper, plus up to 3 additional Tablespoons milk if needed to reach your desired consistency. Serve hot.