Preheat the oven to 180°C/350°F/gas 4. Place 120g of the flour and a pinch of sea salt in a large mixing bowl. Crack in the eggs and whisk together, then gradually pour in 70ml of milk and 70ml of water, whisking as you go, then put aside. Put a saucepan on a medium heat with 1 tablespoon of olive oil. Peel, finely slice and add the garlic and cook for 2 minutes, or until softened. Stir in the remaining flour and very gradually pour in the remaining milk. Stir in the mustard, frozen spinach and season with a pinch of salt and black pepper. Put a 26cm frying pan on a medium heat with 1 tablespoon of oil. Add just enough batter to coat the base of the pan, gently swirling to cover. Cook until lightly golden, then flip and cook on the other side. Repeat with the remaining batter, wiping out the pan with a ball of kitchen paper and adding a tiny drizzle of oil each time – you should end up with 6 crêpes. Meanwhile, grate the cheese and tear up the ham. Get yourself a deep ovenproof pan, 26cm in diameter. Repeat layers of crêpe, spinach sauce, ham and cheese until you’ve used up all the ingredients, finishing with a layer of sauce and cheese. Bake on the top shelf of the oven for 30 minutes, or until golden and bubbling, then rest for 10 minutes before serving. Click apart the lettuce leaves, toss with 3 tablespoons of oil and 1 tablespoon of red wine vinegar, season with a pinch of salt and pepper and serve alongside the pancake stack.