Cook the sausage in a skillet over medium heat, breaking it apart if needed, until browned and cooked through, about 8-10 minutes. The sausage should be nicely browned and smell savory.
Transfer the cooked sausage to a large mixing bowl while still warm, allowing the flavors to meld.
Add the thinly sliced apples and chopped onions to the bowl with the sausage. Mix gently to combine, ensuring the apples are coated with the sausage juices.
Season the mixture generously with salt, black pepper, and dried sage or thyme. Toss again to evenly distribute the herbs and seasoning.
Preheat your oven to 375°F (190°C). Grease a baking dish and spread the sausage and apple mixture evenly inside.
In a small bowl, combine the bread crumbs, grated Parmesan, melted butter, and paprika. Mix until the crumbs are evenly coated and fragrant.
Sprinkle the breadcrumb mixture generously over the top of the sausage and apple filling, covering the surface completely for a crispy topping.
Bake uncovered in the preheated oven for 25-30 minutes, or until the top is golden brown and bubbling around the edges. The aroma of baked spices and cooked apples will fill your kitchen.
Remove from the oven and let sit for a few minutes to settle. The topping should be crisp, and the filling tender and fragrant.
Serve warm, garnished with fresh herbs if desired, and enjoy the comforting blend of savory sausage, sweet apples, and crunchy topping.