Heat oil in a non-stick skillet over medium-high heat. Stir in onion and mushrooms; cook 5 minutes or until softened and lightly browned at edges. Stir in spinach and red pepper flakes. Remove skillet from heat and set aside. In a blender, add the 1/4 cup sun-dried tomatoes and puree until smooth; set aside.
Preheat oven to 350 degrees Fahrenheit.
On a lightly floured work surface, cut dough into 6 equal pieces. With a rolling pin, roll each piece into a 6-inch diameter. Spread 1 teaspoon of the sun-dried tomato paste over 1 dough circle. Place 1 slice of beef in center. Top with 1/2 a Provolone slice, some of the Mozzarella, some of the vegetable mixture, a piece of the roasted red pepper and Parmesan cheese. Fold circle of dough in half and press with fork to seal edges.
Place calzone on a foil-lined baking sheet that has been sprayed with cooking spray. Repeat with remaining dough and ingredients. Bake about 30 minutes or until evenly browned and heated through. Serve hot or warm.
