In a large skillet over medium-high heat, sauté chopped onions and mushrooms in 2 teaspoons olive oil until they are soft and the onions are translucent.
Reduce heat to medium. Add minced garlic and chopped eggplant from the Eggplant Prep and cook, stirring frequently, until eggplant is almost fully cooked.
Push eggplant mixture to the sides of skillet and add the mild Italian sausage to the center. Cook sausage, breaking up as you go, until it is fully cooked.
Reduce heat to medium-low. Add Kosher salt, dried basil and oregano, pepper, hot sauce (optional) and diced tomatoes. Bring mixture to a simmer and cook, stirring occasionally, until mixture has reduced and no watery liquid remains in the pan when you pull the mixture away. Remove skillet from heat.
To the mixture in skillet, add ½ cup bread crumbs and 2 ounces of grated Romano cheese. Give it one good stir to incorporate everything together.
Using a large spoon, evenly divide the filling between the eggplant halves. Bake uncovered for 30-35 minutes.
Serve on a bed of baby arugula. Finish with a generous drizzle of balsamic glaze and a sprinkling of Romano.