Old favourites are well-loved for good reason and this upscale bangers and mash is our take on the eternal classic with satisfying pork and fennel sausages, creamy mashed potato, and umami-rich caramelised onion gravy.
Peel and chop potatoes into 3cm pieces. Place in a saucepan of cold, salted water over high heat and bring to the boil. Cook for 15 minutes or until potatoes are cooked through and almost falling apart. Drain well.
Peel and thinly slice onion. Heat a medium, non-stick frypan over medium-high heat. Add sausages and cook, turning occasionally, for 6–8 minutes or until browned on all sides. Cover with a lid and cook for a further 5–6 minutes or until cooked through. Set aside and keep warm.
Meanwhile, heat ½ the butter in a separate frypan over medium-low heat. Add onion and thyme, cover with a lid and cook, stirring occasionally, for 8–10 minutes or until softened and starting to caramelise.
Add flour to onion and cook for 1 minute. Add red wine vinegar and stir for 30 seconds. Dissolve stock cube in 310ml (1¼ cups) boiling water and gradually add to pan, stirring to prevent clumps forming. Simmer for 4–5 minutes or until gravy has thickened. Season with pepper. Add baby spinach leaves and cook until just wilted. Set aside and keep warm.
Meanwhile, return potatoes to saucepan with remaining butter and milk. Using a potato masher, mash potatoes until smooth. Season with salt and pepper.
Divide mash and sausages between plates and spoon over caramelised onion gravy. Season with more black pepper to serve.