Mix the crushed Weetbix with milk and peanut butter to form Weetbix base.
Tip base mixture into a cupcake tray and press firmly to make an even layer. Leave to set.
In a separate bowl, whisk together Greek yoghurt, egg and a squeeze of lemon juice to form cheesecake mixture.
Add the frozen berries to cheesecake mixture.
Spoon it on top of the Weetbix base and spread evenly.
Bake or Microwave at 180 °C convection setting for 15-20 minutes.
Let it cool and set completely before serving.