Combine the quinoa and chicken 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.
Preheat the oven to 375 degrees.
In a small bowl combine the bread crumbs, oregano and garlic powder. Briefly set aside.
Heat ½ tablespoon of olive oil in a large (12-inch) ovenproof skillet over medium-high heat. When the oil is hot and shimmering, add the sausage and cook for about 6 minutes, stirring and breaking up the meat into small pieces with a spatula, until lightly browned. Transfer to a bowl and briefly set aside.
Reduce the heat to medium and add the remaining tablespoon of oil to the skillet. When the oil is hot, add the bell pepper, mushrooms, and onion and cook for about 5 minutes until the vegetables are just tender. Transfer half a cup of the cooked vegetables to a small bowl. (You’re going to use them for the top of the quinoa bake.)
Stir in the cauliflower rice and cook for about 2 minutes until just tender.
Turn off the heat and fold in the quinoa, 2/3 of the sausage, most of the jalapeños (if using), 1¼ cup of marinara sauce, and ¾ cup of the cheese. Taste the filling and season with a little salt if needed. Gently smooth the top of the quinoa bake with a spatula.
Spread the remaining ½ cup of tomato sauce on top of the filling then sprinkle with the remaining ¾ cup cheese. Top with the remaining sausage, the reserved vegetables and jalapeños (if using), and sprinkle with the bread crumb mixture.
Bake for 25 minutes, or until the cheese has melted and the top is very lightly browned.
Let your delicious quinoa bake cool for a few minutes. (It will remove your taste buds if you cheat.) Serve with crushed red pepper and grated Parmesan cheese if you’re feeling festive.