1. Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper or lightly grease it to prevent sticking.
2. In a large mixing bowl, toss the cubed sweet potatoes with olive oil, cinnamon, salt, and pepper until evenly coated.
3. Spread the sweet potatoes out in a single layer on the baking sheet. Roast for about 25 minutes, stirring once halfway through, until they start to soften and caramelize.
4. While the sweet potatoes roast, toast the walnuts in a dry skillet over medium heat for 3-5 minutes, shaking frequently, until fragrant and lightly browned. Set aside.
5. After 25 minutes, remove the baking sheet from the oven. Drizzle the maple syrup evenly over the sweet potatoes and sprinkle the toasted walnuts and fresh thyme on top.
6. Return the pan to the oven and roast for an additional 10-12 minutes, or until the sweet potatoes are tender and the syrup is bubbling and slightly sticky.
7. Remove from the oven and let cool for a few minutes before serving. This resting time lets the flavors meld and the syrup thicken just enough to coat each bite.

Here’s a little tip I picked up from those afternoons with my grandmother: don’t rush the roasting. That slow caramelization is where the magic lives. Stirring halfway through helps ensure every cube gets that golden edge. And toasting the walnuts separately? It really brings out their flavor and crunch.