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.