The fillings and pizza dough for my calzones can all be prepared ahead of time, and then the fillings can be easily encased in pizza dough and baked within minutes.
Heat large griddle or sauté pan over medium-high heat. Add 1 tablespoon oil.2.
Season steaks with salt and pepper. Sear steaks 3 minutes per side, or until deep brown and cooked to medium-rare doneness. Set steaks aside on plate.3.
Add bell peppers, onions, and 1/2 tablespoon oil to griddle and cook without stirring for 2 minutes. Stir in garlic and continue cooking for 2 minutes, or until onions and peppers are caramelized. Remove from heat to cool.4.
Thinly slice steaks and then transfer steak slices and any juices to onion-pepper mixture. Set aside.5.
Position 1 oven rack in center and second rack on bottom of oven and preheat to 500°F. Line 2 heavy large baking sheets with parchment paper.6.
Roll out each piece of pizza dough into an 8-inch-diameter round.7.
Mix cheeses in bowl. Sprinkle 1/2 cup cheese mixture over lower half of each pizza dough, leaving a 1-inch border. Spoon beef mixture over cheeses. Sprinkle remaining cheese mixture over beef mixture.8.
Fold plain dough halves over filling, forming half circles. Press and pinch edges of dough firmly together and crimp to seal.9.
Transfer calzones to prepared baking sheets. Bake about 8 to 10 minutes, or until calzones puff and become golden brown. Brush extra-virgin olive oil over calzones and serve with marinara sauce.