
Basic cheese on toast is a superb quick and easy tummy filler, but this slightly more elaborate version takes it to the next level. It really is The Best Cheese On Toast You'll Ever Have. And it's still quick, easy and cheap to make.

4 slices thick cut white bread
1 small red onion
mature cheddar cheese
grated parmesan cheese (optional)
1 tsp wholegrain mustard
1 tbsp butter