Place chopped onion in a small pot the butter. Cook slowly until onion becomes transparent in colour. Add flour and stir in and cook until mixture feels a little like sand. Do not burn your fingers or the flour!
Having warmed the milk with bay leaf in it. Slowly add milk a little at a time, making sure you stir in properly, beating the mixture with a wooden spoon to remove any lumps.
Next add the grated cheese and a shake of Worcester sauce, allow to cool. Then add the yolks of two eggs, then let it cool down and get thinner.
Meanwhile, rub some olive oil into two thick slices of bread, cook them on a griddle plate or just toast.
Spread mixture very thick on the toast and grill until golden brown.
*TIP: You can keep the mixture in the fridge for up to 3days or place it in the freezer.
Recipe by Chef Rogers Stephens