Step 1

Beat the butter with an electric whisk until it turns pale. Add the beaten egg and egg yolks, one spoonful at a time, and continue mixing until pale and fluffy. Add the rum and beat together once more.

Step 2

Add the remaining ingredients and mix together by hand very gently to pull it into a dough, but be careful not to overwork the mixture or it will become greasy. At this stage the dough should feel quite sticky.

Step 3

Dust the work surface and lightly coat your hands with flour. Divide the dough into four equal pieces and roll each into a 2cm wide log. Cut each log on the diagonal into slices approximately 3cm thick. Continue to flour your hands and work surface as you shape each log. Place the biscuits on baking trays lined with baking parchment and chill in the fridge for at least 30 minutes before baking. Preheat the oven to 200°C/180°C fan/gas 6.

Step 4

Once chilled, glaze the top of each biscuit with the egg yolk and sprinkle a little extra grated cheese on top. Bake on the middle shelf of the oven for 15–20 minutes or until golden. Remove from the oven and allow to cool on the tray for 5 minutes before transferring to a wire rack to cool completely.