Preheat: Preheat the oven to 425°F (218°C) for a conventional oven or 400°F (204°C) for a convection oven. Line two baking sheets with parchment paper. See the pan setup note below.
Prepare the squash: Scrub the squash clean and pat dry. Trim off the ends, then slice crosswise into ½-inch-thick rings. Use a small teaspoon to scoop out the seeds and stringy parts. No peeling is needed.
Season: In a large mixing bowl, toss the squash with the salt, pepper, cinnamon, and olive oil until evenly coated.
Roast: Line two baking sheets with parchment paper. Divide the squash between them in a single layer, leaving space between the rings. Place both pans side by side on the middle rack. Bake at 425°F (conventional oven, without fan) for 20 minutes. Flip the rings and continue roasting for another 8–10 minutes, checking at the 8-minute mark. If using a convection oven (fan setting), set to 400°F and start checking a few minutes earlier. The squash is ready when golden brown on the edges and tender in the center.
Make the sauce and dress the greens: Meanwhile, stir all the sauce ingredients together in a small bowl, starting with 1 tablespoon of lemon juice. Taste and add more lemon juice if desired. Cover and refrigerate until ready to serve. Just before serving, toss the arugula with a pinch of salt and pepper and a drizzle of olive oil and lemon juice.
Assemble: Arrange the arugula on a serving platter and place the roasted squash on top. Sprinkle with the dried cranberries and golden raisins, if using. Drizzle lightly with the sauce or serve it on the side. Enjoy warm or at room temperature.
Notes
Pan setup: I use one large baking sheet and one half-sheet pan that fit side by side on my middle rack. If your pans don’t fit together, roast in batches so the squash has room to brown. Allow extra cooking time for separate batches.
Slice thickness: In my testing, ½-inch rings are the sweet spot. They turn tender while holding their shape and work well with the arugula and toppings.
Topping options: For crunch, swap the dried fruit for chopped toasted walnuts, almonds, or pistachios.
Sauce option: Mayonnaise adds creaminess while yogurt brings tang. To skip the mayonnaise, use 5½ tablespoons of plain Greek yogurt in place of both the mayonnaise and regular yogurt. Add a touch of maple syrup if you’d like to balance the acidity.
Storage: Store leftovers in airtight containers in the refrigerator for up to 3 days. Keep the squash, sauce, and greens separate when possible.
Reheating: Reheat the squash on a baking sheet in a 400°F (204°C) oven for 10–15 minutes. Add the arugula, sauce, and toppings after reheating.