|Butter||4 Ounce (100 Gram)|
|Plain flour||4 Ounce (100 Gram)|
|Mustard powder||1⁄4 Teaspoon|
|Cheese||4 Ounce, finely grated (100 Gram)|
|Egg||1 , lightly beaten|
Lightly grease two baking trays.
Cream the butter until very soft, light and fluffy.
Sift the flour with the mustard powder and salt, then stir these dry ingredients into the creamed butter, together with the cheese, and work all the ingredients together to form a firm dough.
Knead lightly, then wrap the dough in cling film and chill for 1 to 2 hours.
Roll the dough out on a lightly floured board into a 23 cm/9 in square.
Divide the square into 3.5 cm/1 1/2 in squares, then cut these in half diagonally to give bite sized triangles.
Using a palette knife, carefully transfer the triangles to the prepared baking trays and brush them with the beaten egg.
Chill any remaining biscuits and cook them as a second batch.
Bake the biscuits in a moderately hot oven (190C, 375 F, gas 5) for 10-12 minutes, or until golden brown.
Remove the hot biscuits from the trays and transfer them to a wire rack to cool completely.