Slice the mushrooms and tomato into thick rounds.

Drizzle a bit of olive oil into a frying pan and cook the mushrooms over a medium heat for 5 minutes until they just start to brown. Remove the mushrooms and set to one side.

Add another drizzle of oil into the pan and cook the tomato slices and chopped chives for another 5 minutes over a high heat, until the edges start to blacken. Remove from the pan and set to one side.

Fill the pan with enough oil to create a thin layer over the bottom of the pan and cook the egg to your liking. Hint: if you want a runny yolk, only cook the egg for about 1 minute, since it will cook more later on.

Whilst the egg is cooking, butter both sides of each slice of bread. Top one side of each slice with the grated cheese.

On one piece of bread, top the cheese with the mushrooms, tomato-chive mix and the egg. Carefully fold the other piece of buttered bread and cheese on top to create a sandwich.

Cook the buttered sandwich for 5 minutes on either side, until golden brown.

Slice in half and serve immediately whilst hot.