There are recipes that demand three hours of prep and five different kitchen appliances. And there are recipes that need one lemon, one bowl and an electric mixer. This one - lemon biscuit with the peel - is of the second type. Spanish actress María Castro makes it in a few steps, and the result, according to her, is "incredible."

The trick is that the lemon goes whole into the batter - peel and all. What would otherwise be a bitterness problem from the white pith is solved by boiling the lemon for 5 minutes before adding it to the mix. Five minutes - and all the aromatic oils stay, while the bitterness leaves with the water.

What you need:

• 1 lemon (whole, cut into pieces, pre-boiled for 5 minutes)
• 160 g sugar
• A pinch of salt
• 3 eggs
• 60 ml oil
• 60 ml milk
• 1 sachet of baking powder
• 170 g flour
• A little vanilla

How to make it: Put the boiled lemon in a bowl. Add the sugar, salt, eggs, oil, milk, baking powder, flour and vanilla. Beat with an electric mixer until you have a smooth mixture - about two minutes. Pour into a tin greased with oil and dusted with flour. Bake at 170°C with top and bottom heat for one hour.

These quantities give a medium-sized biscuit for 6-8 slices. Warm with a cup of tea is best, but it also works in the morning with coffee. When you take it out of the oven, don't cut it while it's hot - let it sit 15 minutes to settle, otherwise it breaks. That's the biggest mistake in the process, and the reason some biscuits "don't succeed" even when everything is by the recipe.

Why does this recipe work? Because the bitterness of the white pith - which would otherwise be a problem - is balanced with the sugar and with the aromatic oils that give an intense lemon flavour. With 9 ingredients and no technique, you get something that can stand in line with restaurant biscuits - and be cheaper.