Combine base ingredients in a mixing bowl.
Press two-thirds of the mix into a baking tray and bake for 10 minutes.
Microwave all caramel ingredients, except for zest, for four minutes.
Whisk well and microwave for two more minutes.
Pour the caramel mix over the base and sprinkle lemon zest over top.
Crumble the remaining base ingredients on top of the caramel and bake for 15-20 minutes.
