Preheat oven to 180C/350F/Gas 4 and line a 7 x 11" baking pan with parchment paper, leaving an overhang.

Sift the flour, baking powder, and salt into a mixing bowl and set aside.

Using an electric stand or hand mixer, beat the butter, peanut butter, and sugar on medium until smooth and combined.

Add in the egg and vanilla extract to the mixing bowl and beat until all the ingredients are well combined.

Add the flour mixture into the peanut butter mixture and stir together with a large spoon or spatula to form a thick, almost dough-like batter.

Place three-quarters of the batter into the prepared baking pan and press to flatten evenly.

Spread the strawberry jam evenly on top of the dough batter.

Break off small pieces of the remaining one-quarter batter and scatter over the jam.

Then sprinkle the salted peanuts on top of the jam and dough.

Place in oven and bake for 25-30 minutes.

Remove from the oven and leave to cool completely in the pan.

Lift out using the parchment paper overhang and cut into bars.