I find using grated cheese is better than sliced as it starts to melt a little more quickly.. Get the grill nice and hot and as soon as the cheese starts to melt, using a flat knife, smear the melting cheese right to the edges of the toast. That will protect the edges from burning. If you want something extra tasty, smear a little pickle or your favourite chutney on the second side of the bread, before you sprinkle on the cheese. Geeta's spicey mango chutney is particularly delicious if you like an Asian flavour.