Peel, trim and coarsely grate your parsnips. Pop in a heatproof bowl. Cover with boiling water and leave to soften while you prepare your filling.
Peel and chop your onion. Peel the carrot and cut into small cubes. Roughly chop the tomatoes.
Crumble the stock cube into a heatproof jug. Pour in 200ml boiling water. Stir to dissolve and set aside.
Heat 1 tbsp oil in a pan. Add the onion and carrot. Fry for 3 mins. Add the beef mince and cook for 4 mins till browned. Measure in 1 tsp smoked paprika and stir.
Add the chopped tomatoes and the beef stock. Bring to a simmer, then cover. Cook for 15 mins. Heat your grill to its highest setting.
While the mince is cooking, thickly slice the leeks. Melt the butter in a pan. Add the leeks and cook over a low heat for 10 mins till soft. Season. Pop on a lid to keep warm whilst you finish the rest of the dish.
Drain the parsnips and squeeze out as much water as possible. Pour in ½ tbsp oil and season. Add 1 tsp paprika and toss together.
After the mince has cooked for 15 mins, taste and season. If your pan isn’t ovenproof, spoon into an ovenproof dish. Heap the parsnips on top. Slide under the grill and cook for 4-5 mins, keeping a close eye. It should have a crispy, golden appearance, with the edges slightly blackened. Serve with the buttery leeks.