Toss squash cubes with olive oil, maple syrup, and sprinkle all over with 1/2 teaspoon sea salt, pepper, and ground chili. Arrange on baking sheet. Roast 20 minutes, toss, and continue roasting until the edges of the squash crisp up and are just turning golden, 10 - 15 minutes more.
Meanwhile, toss the red onions with lemon juice and a big pinch sea salt, and set aside.
To make the dressing, toss the minced red onions with lemon juice, a pinch of sea salt, and Dijon, and set aside 5 minutes. Whisk in the maple syrup and then slowly add the olive oil, whisking until mixture is emulsified.
To assemble the salad, toss the apples and greens with a drizzle of vinaigrette. Taste as you go and add sea salt as needed. Arrange greens and apples on a platter, layer with butternut squash cubes and shaved cheese. Top with pumpkin seeds, more dressing, and lots of black pepper. Serve right away.