For the fool, mix together all of the ingredients in a bowl, then pour into a tall dessert glass.
For the brittle, melt the sugar in a saucepan over a high heat until golden, then remove from the heat.
Add the sesame seeds and stir well. Pour onto a clean baking sheet and place into the freezer to cool. Once set, remove from the freezer and cut up the brittle and use to garnish the fool.