Preheat your oven to 400°F (200°C) and lightly grease a 9x13-inch baking dish with unsalted butter or olive oil.

Peel and thinly slice 2-3 medium sweet potatoes into 1/8-inch thick rounds and place in a large mixing bowl.

Melt 2 tablespoons of unsalted butter in a medium saucepan over medium-high heat. Add 2 minced garlic cloves and 1 minced shallot. Sauté for 2-3 minutes until fragrant.

Stir in 1 tablespoon of fresh thyme, a pinch of kosher salt, and black pepper. Remove from heat and pour in 1 cup of heavy cream and 1/2 cup of Parmesan cheese. Stir until melted.

Pour the creamy mixture over the sliced sweet potatoes and toss gently to coat all slices with the herb-infused cream.

Transfer the coated sweet potatoes to the prepared baking dish, arranging the slices upright and overlapping slightly.

Bake in the preheated oven for 50-60 minutes until fork-tender and the top is golden brown.

Allow to cool for a few minutes, garnish with fresh thyme, and serve warm.