Chocolate, peanut butter & pretzel cookie bars

Heat oven to 180C/160C fan/gas 4. Grease and line a 20cm square baking tin with baking parchment. Tip the butter, sugars and vanilla extract into a bowl and beat with an electric hand whisk until smooth and creamy. Add the eggs bit by bit, beating well between each addition. Stir in the flour, bicarb and 1/4 tsp salt until the mixture forms a dough, then add the milk and 100g chocolate chunks.

Spoon half the mixture into the tin, add the peanut butter in dollops to cover the surface, then top with the remaining dough. Use your fingers to press everything down, but don't worry about it looking too neat. Arrange the pretzels on top and bake for 50 mins until the dough is set and crisp on the surface. Leave to cool in the tin to room temperature before cutting.

Melt the remaining chocolate in a bowl over a small pan of gently simmering water, or in short bursts in the microwave. Remove the bars from the tin and drizzle with the chocolate, then sprinkle with the sea salt. Leave to set, then cut into bars.