Recipe courtesy of Nourish and Flourish, a Veracity Media Group Publication
Set the EGG for indirect cooking with a convEGGtor at 400°F
Spread the pat of butter and olive oil in the cast iron skillet. Slice sweet potatoes, parsnips, and beets into thin rounds, using a mandolin, slicing blade or a food processor; transfer each vegetable to its own bowl.
Pour ⅔ cup of cream over each bowl of vegetables and top each with 2 tablespoons of parmesan and 1 teaspoon of thyme. Season each bowl generously with salt and pepper and toss until all slices are well coated.
Pour remaining cream into a small bowl with the minced garlic and 2 tablespoons of the parmesan and mix well. Pour into the bottom of the prepared skillet.
Take a stack of the sweet potatoes and line the inner edge of the skillet tightly, overlapping slices until a complete circle is formed. Continue with the other vegetables, alternating by color, to create the floral pattern.
Season the top of the gratin with salt and pepper and remaining parmesan cheese. Cover with foil and bake for 25-30 minutes, or until vegetables are soft and knife inserts easily. Remove from the EGG, top with Gruyère and put the skillet back onto the EGG until the top is golden brown and bubbly. Finish with a sprinkle of fresh thyme.