I've made this variation of a pizza many a time for Louis. It's fairly low in salt, sugar and fat.
All you need is bread, tomato purée, oregano and cheese.
Lightly toast the bread and spread the tomato purée on it like you would butter. Sprinkle on some oregano, grate or slice some cheese on top and put under the grill until the cheese has melted.
Et voila! Quick and easy pizza!
You can add extra bits like ham with the cheese. If you want to add peppers, mushrooms, onions etc. Lightly fry them and then add at the same time as the cheese.
You can also use pitta bread pockets instead of conventional sliced bread. You just need tocut around the edge of the pocket so you get two halves and by-pass the toasting stage.