As I meant to search for this and not ask it, I feel compelled to apologise, and now answer it!

Marshmallows aren't easy to come by in the UK, but when you find them, buy them, because Rice Krispy Treats are the easiest, most delicious things around.

Melt 50g butter and mix in approximately 300g of marshmallows. Once melted, add 6 cups of Rice Krispys, mix quickly and spread into greased 9x13 pan. Let cool and eat! Needless to say, especially good for kids, or if you ate them as a kid : )