For the choux potatoes, line a baking tray with cling film.
Mix 110g/4oz of the butter in a bowl with the wild garlic until well combined. Spoon the mixture onto a piece of greaseproof paper and roll it up into a cylinder. Chill in the fridge until set.
Heat the remaining 65g/2oz butter and 110ml/4fl oz water in a saucepan until the butter has melted. Stir in the flour and continue to cook, stirring constantly, until the mixture leaves the side of the pan.
Slowly beat in the eggs, one at a time, then the mashed potato until well combined. Season with salt.
Spoon the mixture onto the baking tray and chill in the fridge.
Heat a deep-fat fryer to 170C/325. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
Slice the chilled butter in rounds.
Flour your hands lightly, then shape some of the potato mixture around a slice of butter to form a neat ball. Fry the choux ball for 2-3 minutes, or until golden-brown. Remove from the oil and set aside to drain on kitchen paper. Repeat with the remaining butter slices and potato mixture.
Meanwhile, for the lamb, preheat the oven to 200C/400F/Gas 6.
Heat an ovenproof frying pan until hot. Add the oil, lamb, rosemary sprig and garlic clove. Seal the lamb on all sides, then add the baby carrots to the pan and make sure that they are well coated in the oil.
Roast the lamb in the oven for 6-8 minutes (for medium), or until cooked to your liking. Turn the lamb half way through the cooking time.
Remove the lamb from the frying pan and set aside to rest.
Return the frying pan to the heat and de-glaze the pan with the vinegar. Add the stock and simmer for 4-5 minutes. Remove the garlic clove and rosemary and whisk in the butter.
Meanwhile, preheat the grill to high.
Blend the brioche, rosemary and parsley in a food processor until well combined.
Mix the maple syrup and mustard together in a bowl, then brush this mixture over the lamb. Firmly press the breadcrumb mixture onto the lamb. Grill the lamb for 2-3 minutes.
To serve, arrange the carrots on serving plates. Drizzle some sauce onto the plates, slice the lamb and lay over the sauce, then scatter the choux potatoes around the edge.