Heat the oven to 160C fan. Butter and line the base and sides of a 20cm square cake tin with baking parchment.
Put 3 tbsp each of the peanut butter and jam in separate small bowls and set aside. Tip the remaining peanut butter, the rest of the jam and the butter and sugar into a bowl set over a medium heat and stir until everything has melted together. Quickly stir in the oats, then leave to cool for 5 mins.
Spoon the mixture into the prepared cake tin and gently press down with your hands. Dot over the reserved peanut butter and jam, then bake for 20-25 mins or until golden brown. Leave to cool completely in the tin, then turn out onto a board and cut into squares.