Clean and cut sweet potatoes to 1/2-inch thick rounds (you can either keep the skin on or peel it).

Preheat oven to 200°C / 400°F.

To sliced sweet potatoes, add melted butter, 1 teaspoon cinnamon, salt, and pepper. Mix well using a spatula or your hands. Alternatively, use a ziplock bag to shake and mix.

Arrange sweet potato slices on a baking tray in a single layer, leaving little space between slices. Bake for 25-30 minutes.

At the end of the baking time, the sweet potatoes should be tender. Adjust baking time based on slice thickness.

Meanwhile, mix ⅓ cup maple syrup, chopped walnuts, 1/2 teaspoon cinnamon, and thyme in a bowl.

Remove the baking tray and top each sweet potato slice with about 1 teaspoon of the walnut mixture.

Return the tray to the oven and bake for another 8-10 minutes until the sweet potatoes look caramelized around the edges.

Serve as it is or with some feta sprinkled on top.