Melt the butter over a medium heat, before adding the mushrooms and bacon.
When the mushrooms and bacon are cooked through, add the flour and stir in well. Keep stirring for a further couple of minutes to cook the flour.
Remove from heat and pour in the milk and some freshly ground black pepper to taste.
Preheat the grill to hot.
Put the pan back onto the hob and stir continuously until boiling. Remove from heat and stir in three-quarters of the cheese.
Divide the mixture into four ramekins, sprinkle over the remaining cheese and place under the hot grill until golden brown and bubbling. Serve with brown bread.