Place the digestives in a plastic bag, remove all the air and tie a knot in the top. Crush the digestives into crumbs by gently hittingÂ with a rolling pin. Alternatively you can break down the biscuits in a food processor.
In a bowl stir the melted butter into the crushed digestives.
Transfer the biscuit mix to a lined or greased square baking tin (9" x 9"). Use a spatula to press down the biscuit; making sure it reaches into all the corners and is evenly spread across the base of the tin. Place the tin in the fridge for 20 minutes in order to set the biscuit base.
Whilst the biscuit is in the fridge prepare the peanut filling by mixing together the peanut butter, syrup and vanilla extract.
After 20 minutes remove the tin from the fridge. Carefully spread the peanut mix over the biscuit. Use a spatula or cake slice to get an even finish. Return to the fridge for a further 20 minutes.
Next prepare the chocolate by setting up a bain-maris: pour 1 cm of water into a large pan and bring to the boil. Balance a large heat proof bowl over the top of the pan - do not let the water touch the base of the bowl. Add the chocolate and soft butter to the bowl and let it gradually melt. You shouldn't need to touch the bowl until the chocolate is completely melted. However, be careful of the steam when you do remove the bowl from the pan.
Alternatively you can melt the chocolate and butter in the microwave. Heat for 20 seconds at a time, then check and stir. Repeat until fully melted.
Once the chocolate is melted, set to one side to cool slightly. Remove the tin from the fridge and pour the slightly cooled chocolate over the peanut layer. Spread evenly again using the spatula. Finish off by dragging the spatula lightly across the top of the chocolate in lines from left to right. This will create a ripple effect as it sets.
Leave to set in a cool dry place or if you can't wait that long; return once again to the fridge. However, leaving to set out of the fridge will help the chocolate to retain its shine and colour.
Check to see if the chocolate is set before turning out of the tin and slicing into squares. Enjoy!!