Bacon brioche

• sunflower oil
• 175 g unsmoked streaky bacon, rind removed and cut into small bits
• 1 small onion, peeled and very finely chopped

Heat a film of oil in a frying pan and sweat the bacon until it starts to brown. Add the onion and marjoram, and continue cooking until the onion is softened and the bacon is crisp. Tip on to kitchen paper and leave to drain and cool.

Put the butter in the bowl of a table-top electric mixer, or into a mixing bowl if using a hand-held mixer. Beat until soft and creamy. Beat in the eggs o