Preheat your oven to 375°F (190°C).
In a skillet, cook the sausages over medium heat until browned on all sides.
Transfer the sausages to the oven to finish cooking for about 15 minutes.
While the sausages are cooking, prepare the mashed potatoes.
Boil peeled potatoes in salted water until tender.
Drain the potatoes and mash them with butter and milk until creamy.
In the same skillet, add sliced onions and cook until caramelized.
Pour in the onion gravy and let it simmer for a few minutes.
Once sausages are cooked, place them over the mashed potatoes.
Drizzle onion gravy over the sausages and garnish with parsley.