In a medium bowl, whisk together 3 tablespoons of the olive oil, the vinegar and 1/2 teaspoon of the salt. Set aside.
Place the squash wedges on a rimmed baking sheet. Drizzle with the remaining 2 tablespoons olive oil and 1 teaspoon salt. Add the rosemary and garlic. Cover the tray tightly with a sheet of foil. Bake until the tip of a knife goes into the squash easily, 35 to 40 minutes.
Drizzle three-quarters of the vinaigrette over the squash and allow it to cool and absorb the dressing for about 10 minutes.
Add the arugula, pistachios and cherries to the remaining vinaigrette. Toss gently to coat. Place the marinated squash wedges on a platter and top with the dressed greens. Sprinkle with the gorgonzola and serve.