Step 1

Preheat the oven to 375°F (190°C).

Step 2

Make the purée: In a medium pot, heat the olive oil over medium heat until it begins to shimmer. Add the onion, sweet potato, potato, apple, thyme, and salt. Sauté for 8–10 minutes, until the vegetables begin to release their juices and soften.

Step 3

Add ½ cup (120 ml) of vegetable stock and cover the pan. Reduce the heat to medium-low and cook for 20–25 minutes, until the vegetables are completely softened. Remove the pot from the heat.

Step 4

Remove the thyme stems and discard. Add the remaining ¼ cup (60 ml) of vegetable stock and, using an immersion blender, blend until completely smooth. Season with more salt to taste.

Step 5

Spread the purée over the bottom of an 10-inch (25 cm) cast iron skillet. Arrange the orange sweet potatoes, yellow potatoes, purple sweet potatoes, delicata squash, and apple slices in an alternating pattern on top, working from the outside in. Drizzle the olive oil over the top and season with the salt, pepper, and thyme.

Step 6

Cover the pan with foil and bake the ratatouille for 30 minutes, then uncover and bake for another 20–25 minutes, until the vegetables are softened and starting to brown.

Step 7

Drizzle the ratatouille with more olive oil to taste. Serve warm.

Step 8

Enjoy!