Preheat the oven to 425°F and line a baking sheet with parchment paper.
Place the squash and onions on the baking sheet. Drizzle with olive oil and sprinkle with salt and pepper. Toss to coat and arrange on the sheet so that they’re not touching. Roast until the squash is golden brown on all sides and until the onions are soft and browned, 25 to 30 minutes.
Make the dressing: In a small bowl, whisk together the olive oil, apple cider vinegar, garlic, mustard, maple syrup, and a pinch of salt and pepper. Set aside.
In a small pan over medium-low heat, toss the pepitas with a pinch of salt and cook until toasted, stirring frequently, for about 2 minutes. Set aside.
In a medium mixing bowl, combine the kale, sage, and thyme. Add the warm roasted squash and onions, the apples, half the pepitas, and half the dressing. Toss to coat. Transfer to an oven-safe serving dish. (If you’re making this dish in advance stop here and follow the saving/reheating instructions in the notes below).
Place the serving dish into the oven for 8 to 10 minutes, or until the apples and kale are warm and the kale is just wilted. Just before serving, drizzle with the remaining dressing, and top with the remaining pepitas.
Notes
Make-ahead instructions: Once the roasted vegetables are transferred to the serving dish, cool to room temp. Cover with foil and chill the dish until ready to reheat (Ideally, make this around 4 hours in advance). When ready to reheat, preheat the oven to 425°. Loosen the foil and bake, very loosely covered for 12 to 15 minutes or until everything is heated through. Just before serving, drizzle with the remaining dressing, and top with the remaining pepitas.