Preheat oven to 400 degrees F.

Prepare a rimmed baking sheet.

Toss the squash with 2 tablespoons olive oil and 3/4 teaspoon salt on the baking sheet.

Roast the squash until golden brown and tender, approximately 20 to 25 minutes.

While the squash is roasting, bring the apple cider to a boil in a small saucepan.

Reduce heat and simmer until the cider liquid has reduced to 1/4 cup, approximately 12 to 15 minutes.

In a medium bowl, whisk together the reduced cider, red wine vinegar, mustard, remaining 2 tablespoons olive oil, 1/4 teaspoon salt, and 1/4 teaspoon pepper.

Stir in the chopped fresh flat-leaf parsley.

Transfer the roasted squash to a serving platter.

Drizzle the cider vinaigrette over the squash just before serving.