Toast pine nuts in a small pan over medium heat until golden. Place spinach, arugula, garlic, cheese, 2 pinches salt, a few grinds black pepper, nutmeg, and toasted nuts in a food processor. Pulse grind the filling into a paste. Taste and adjust seasonings. Remove 1/2 cup of filling paste to a bowl and stir in extra-virgin olive oil to loosen it. Reserve remaining filling in processor bowl.
Place steaks between layers of waxed paper several inches apart. Pound steaks with a heavy bottomed pan to 1/2 their thickness. Season each steak with salt and pepper on both sides. Cover each steak with a thin layer of filling and top with roasted red peppers. Roll steaks tightly and cut each steak in 1/2 across. Secure pinwheels with a carefully placed skewer and set 6 pinwheels on a baking sheet. Drizzle with extra-virgin oil and roast 12 to 15 minutes. Remove skewers and transfer pinwheels to dinner plates. Top each with a generous portion of reserved sauce made from filling and extra-virgin olive oil, combined.