When the butter is really soft, tip it into a bowl along with the sugar. Using an electric hand whisk or exercising some arm muscle, beat together until the sugar is mixed through. Beat in the eggs, one at a time, followed by the vanilla extract and a pinch of salt, if you like. Stir in the flour and oats. The mixture will be quite stiff at this point. Now decide what else you would like to add any or all of the flavours are delicious and stir through.
Tear off an A4-size sheet of greaseproof paper. Pile up half the mixture in the middle of the sheet, then use a spoon to thickly spread the mixture along the centre of the paper. Pull over one edge of paper and roll up until you get a tight cylinder. If you have problems getting it smooth, then roll as you would a rolling pin along a kitchen surface. Youll need it to be about the width of a teacup. When it is tightly wrapped, twist up the ends and then place in the freezer. Can be frozen for up to 3 months.
To cook, heat oven to 180C/fan 160C/gas 4 and unwrap the frozen biscuit mix. Using a sharp knife, cut off a disk about cm wide. If you have difficulty slicing through, dip the knife into a cup of hot water.
Cut off as many biscuits as you need, then pop the mix back into the freezer for another time.
Place on a baking sheet, spacing them widely apart as the mixture will spread when cooking, then cook for 15 mins until the tops are golden brown. Leave to cool for at least 5 mins before eating.
