Cider & leek Welsh rarebit toast

Preheat the grill to medium-high. Melt the unsalted butter in a pan and cook the leeks with a pinch of salt over a low heat for 5-7 minutes until soft. Add 2 tbsp of the dry cider and simmer until evaporated. In a bowl, mix the grated mature Cheddar with the mozzarella, egg yolks, remaining 3 tbsp dry cider, wholegrain mustard, Worcestershire sauce and ground black pepper. Stir through 1⁄3 of the leeks. Lightly toast the 4 slices of bread. Spread the cheese mixture on top; grill. Transfer to plates, spoon over the remaining leeks and scatter over the chopped chives.