Preheat the oven to 400°F. Cover a baking sheet with parchment paper.
Coat the sweet potato slices with olive oil. Spread them out on the baking sheet. Season with salt and pepper. Bake for 20 minutes, until soft.
Lightly grease a small baking dish.
In a bowl, mix the pumpkin seeds, sunflower seeds, honey, cayenne, and salt. Transfer it to the baking dish. Put it in the oven alongside the sweet potato for 5-7 minutes, until lightly golden. Remove and let cool. Once cooled, remove the seeds and break them up into clusters.
When the sweet potatoes are done, remove from the oven and let cool.
Spread the mascarpone onto the sweet potato rounds. Top with the nut clusters. Garnish with fresh thyme.