Step 1

Spray the frying pan with low calorie cooking spray and sauté the mushrooms and spring onion for 2-3 minutes until soft. Place in a bowl.

Step 2

Pre-heat the grill to high.

Step 3

Allow the mushrooms to cool slightly, then add the grated cheese, mustard powder, Henderson's relish and egg yolk. Add a little freshly ground black pepper to taste.

Step 4

Slice the muffins and place them cut side down on a baking sheet. Pop them under the grill and toast the bottoms until golden and crisp.

Step 5

Turn the muffins over, but don't toast the top side yet! Reduce the grill to medium.

Step 6

Spread the cheese and mushroom mixture evenly over the tops of the muffins and pop back under the grill for 2-3 minutes until the cheese has melted and gone golden.

Step 7

Serve! We love this with some rocket and roasted or grilled tomatoes.