300g all-purpose flour
a pinch of salt
1 tsp bicarbonate of soda
170g butter, melted
300g caster sugar
1 egg yolk
a few drops of vanilla extract
Preheat the oven to 160°C/320°F. Grease a rectangular baking tin (approx. 30 x 20 cm) with butter or oil.
Mix butter and sugar until pale and fluffy. Whisk in the egg, egg yolk and vanilla. Add dry ingredients and mix until you have a smooth cookie dough.
Stir in the M&M’s, then press the cookie dough into the baking tin. Bake for 25 to 30 minutes, or until golden brown on top.
Allow to cool down completely before slicing into equally sized bars.