Line the bottom of the grill pan with foil. Put grill on a medium to high setting.
Finely slice the mushrooms and place in a microwavable bowl. Add the butter and soy sauce and cook on full power for 1 min.
Toast bread and place on grill. Pour a spoonful of the butter/soy sauce from the cooked mushrooms onto the bread, then arrange a layer of mushrooms onto each slice of bread.
Continue to layer up the toast with the mushrooms, cheeses and tomatoes, making sure that the toast is covered to the very edge. Make sure you end with a layer of cheese then drizzle a good slug of Worcester sauce over the top of both slices when done.
Put under grill and cook until the cheese bubbles and begins to brown.
All ingredients are added to your own personal taste. You could also add chillies for a bit of extra spice! :)