Put the olive oil in a pan with the garlic and anchovies and stir over a low heat for a few minutes.
Whisk in 90g of the butter, and as soon as it has melted, remove from the heat and whisk a few more times so that everything is creamy and amalgamated.
Taste, and if you feel you want this dipping sauce, which is meant to be pungent but not acrid, a little more mellow, then whisk in two more tablespoons of butter.
Pour into a fondue dish over a flame or just serve in a very warm bowl.
Serve with the vegetable crudités for dipping.