Preheat oven to 400 degrees F, grease a baking dish and set aside. Evenly layer the sliced sweet potatoes in the dish (shown above).
In a small saucepan heat the butter over medium-high heat. Once warm add in the garlic and shallot, sauté for 2-3 minutes until fragrant. Add in the fresh thyme, salt, and pepper. Remove from heat and stir in the heavy cream. Pour the mixture over the layered sweet potatoes. Top with half of the parmesan cheese.
Bake for 50-60 minutes or until the sweet potatoes are tender. Once tender remove from the oven and top with the remaining parmesan cheese. Broil on high for 1-2 minutes until golden brown, watch carefully so nothing burns.
Garnish with more fresh thyme and enjoy!
Notes
*See images above for how to assemble as well as ingredient substitutions.