Preheat oven to 180C (fan oven) or equivalent

Combine flour, butter and salt. Whiz into fine crumbs. Add water and whiz again. Once large clumps begin to form stop immediately and remove from processor. Press gently together into a ball.

Roll out gently on a lightly floured board to a thickness similar to a pound coin.

Cut out rounds and pat gently into tart tins.

Push remaining pastry lightly together, and cut out the rest.

Fry onion slowly until soft just beginning to colour. Drain on kitchen paper.

Whisk egg and egg yolk together with the mustard powder and peppers. Add cream and whisk in lightly.

Stir in onions and cheese. Divide filling evenly between pastry cases: each one will take roughly a generous teaspoon.

Bake for 15 minutes or until risen and until golden. Serve warm or cold.