Heat the olive oil in a large skillet over medium heat.
Add the sausages and cook, turning occasionally, until browned and cooked through, about 12-15 minutes. Remove from the skillet and set aside.
2. Make the mashed potatoes:
While the sausages are cooking, place the potato chunks in a large pot and cover with water.
Bring to a boil over high heat, then reduce the heat to medium-low and simmer until the potatoes are tender, about 15-20 minutes.
Drain the potatoes and return them to the pot. Add the butter and milk, then mash until smooth. Season with salt and pepper to taste.
3. Prepare the gravy:
In the same skillet used to cook the sausages, melt the butter over medium heat.
Add the flour and cook, stirring constantly, for 1-2 minutes until golden brown.
Gradually whisk in the stock, scraping up any browned bits from the bottom of the skillet.
Cook, stirring occasionally, until the gravy thickens, about 5 minutes. Season with salt and pepper to taste.
4. Serve:
Serve the sausages with the mashed potatoes and gravy on the side, or pour the gravy over the sausages and mashed potatoes. Enjoy your delicious sausage, mash, and gravy!