Heat the oil in a saucepan and sauté the onion until transparent.
Add the broccoli and cook for just one minute.
Pour in the white sauce and bring to a simmer.
Cook over a low heat until the broccoli is soft.
Add 150 g feta and blend in a food processor until smooth.
Heat a large frying pan and cook the bacon until crispy.
Stir into the soup, reserving some for the garnish, then garnish with the remaining feta and bacon.
To make the white sauce, melt 90 g butter in a saucepan and add 90 g flour.
Stir over the heat for one minute.
Remove from the heat and gradually whisk in one litre of milk.
Return to the heat and stir until thickened. Season to taste.