Combine the quinoa and beef broth in a small saucepan and bring to a boil. Lower to a simmer, cover the saucepan with a lid, and cook for 14 minutes, or until all of the liquid has been absorbed. Let the quinoa rest, covered, for 5 minutes, then fluff with a fork.
Pre-heat the oven to 375 degrees.
While the quinoa cooks, prep the panko topping. Heat 2 teaspoons of olive oil in a large ovenproof skillet or sauté pan over medium heat. When the oil is hot and shimmering, add the garlic and red pepper flakes and cook just until the garlic begins to turn golden, about 30 seconds. (Be very careful not to let the garlic burn, friends!) Add the breadcrumbs and cook, stirring regularly until they darken a shade in color and smell toasty, about 2 minutes. Transfer the topping to a bowl and set aside.
Next, cook the steak. Increase the heat to medium-high and add 1 tablespoon of olive oil to the pan. When the oil is hot and shimmering, add the steak to the pan and season with a pinch of salt and freshly ground pepper. Cook for about 2 minutes, stirring constantly and breaking it up into smaller pieces with a spatula, until no longer pink. Using a slotted spoon or tongs, transfer the steak to a bowl or plate and set aside.
Wipe out the pan with a paper towel. Return it to the stove and lower the heat to medium. Add the remaining tablespoon of olive oil. When the oil is hot, add the bell pepper, onion, and mushrooms to the pan. Season with a tiny pinch of salt and freshly ground pepper, and cook for about 7 minutes until the vegetables are tender (but not mushy!). Add the Worcestershire and soy sauce and cook for 30 seconds more.
Return the steak to the pan, then add the cooked quinoa, marinara, and 1 cup of the grated Provolone. Fold everything together until well combined. Taste the filling and season with extra salt and pepper if necessary. Gently smooth the top of the filling, then sprinkle it with the remaining Provolone and the Parmesan cheese and top with the prepared panko mix.
Bake for 20 minutes until the cheese is melted.
Serve garnished with fresh basil and a side dish of warm marinara sauce. (I like to let people add as much marinara as they like to their serving!)