Roast the sweet potatoes: Heat the oven to 425°F (220°C). Slice unpeeled sweet potatoes into 1/3-inch rounds. Toss with 1 1/2 tablespoons oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Arrange in one layer and roast 18 minutes.
Turn and finish: Flip the rounds and roast 10 to 14 minutes more until browned at the edges and tender without collapsing. Cool for 10 minutes.
Make the maple pecans: Toss pecans with maple syrup, cinnamon, remaining oil, and a pinch of salt. Spread on a small parchment-lined pan and bake 6 to 8 minutes, stirring once. Cool completely.
Whip the cheese: Beat goat cheese, cream cheese, heavy cream, lemon zest, remaining salt, and remaining pepper for 2 minutes until light and smooth.
Assemble: Pipe or spoon whipped cheese onto each sweet potato round. Top with maple pecans, pomegranate arils, and thyme.
Serve: Arrange on a platter and serve at room temperature. For the cleanest presentation, assemble no more than 1 hour before serving.
Notes
For best results, verify doneness by the stated temperature and texture cues. Refrigerate perishable leftovers within 2 hours.