Beef Wellington with Madeira Gravy

Ingredients 1kg centre fillet of beef from Thomas Johnston, trimmed (the timings below work perfectly for a fillet of roughly 10cm in diameter) olive oil 2 knobs of unsalted butter 3 sprigs of fresh rosemary 1 red onion 2 cloves of garlic 600g mixed mushrooms 100g free-range chicken livers (cleaned), from Thomas Johnston 1 tablespoon…