Preheat the oven to 180C/Gas4
Melt the butter; add the leek and cook until soft, then cool
In a large bowl, mix the leek with the bread, cheese, asparagus and ham; whisk the remaining ingredients in another bowl, then gently fold into the bread mix
Cut squares of baking parchment with pinking shears, and use to line a 12-hole muffin tin; spoon in the mixture and cover with clingfilm; chill for 30 minutes, then remove the clingfilm and bake in the preheated oven for 25-30 minutes until golden
12 servings