Heat the oven to 190C/170C fan/gas 5 and line two baking trays with baking parchment. Tip the butter, sugar, egg, vanilla and flour into a bowl with a small pinch of salt and beat everything together until completely mixed into a dough.

Tip the oats into a shallow dish. Divide the dough into 24 equal pieces (each should weigh 25-30g), then roll each piece into a ball. Roll the balls in the oats and put 12 on each tray, evenly spaced apart. Flatten each ball down a little then press a cherry half into the middle.

Bake the biscuits for 20 mins, or until golden. Leave to cool on the tray for a few mins then transfer to a wire rack to cool completely. The biscuits will keep for up to three days in a container or biscuit tin.