A favorite of the Bourbon court, was the good fresh butter [sweet, not salted], brought to Paris every Thursday by the women, the children or the domestiques of the plowmen & farmers of those villages surroundings Paris, & the butter of the village of Vanvre[Vamvres--Southwestern outskirts of Paris] was the most excellent; it was usually sold in rolls of three or four ounces for eating on bread, & was much more expensive than other butter, in that it could not be kept for long. Even today, the finest pastries, custards and sauces are made with sweet, not salted, butter.
“The fresh butter most in request for the table in Paris, was that made at Vanvres [Vanves], which in the month of May the people ate every morning mixed with garlic.”
Manners, Customs, and Dress During the Middle Ages and During the Renaissance Period, Paul LaCroix. D. Appleton and Co, New York, 1874, p. 135.
And here is Madame de Pompadour's Asparagus with butter sauce.