En faire tout un fromage is a tasty way to describe an overreaction. When someone greatly exaggerates the importance of an event, they turn it into a whole cheese in French. It literally means "to make a whole cheese about it" and is used to mean "make a big fuss/stink/deal/song and dance about it, make a mountain out of a molehill, create a storm in a teacup.
The expression is also used in its negative form. N’en fais pas tout un fromage, literally “Don’t make a whole cheese of this”: you must not exaggerate the importance of the event we are talking about, or “there’s nothing to whip a cat.”
This idiom was first recorded in the 20th century, although it's thought to have been in use centuries earlier. The origin comes from the idea that starting from not much (milk, a simple food), one can achieve something very elaborated: cheese with taste, complex shapes and textures. After all, when it comes to cheese, les Français en font tout un fromage!
Cheese is so important in France, both culinarily and culturally, that you’d think it had been invented there. In fact, cheese was first made in prehistoric times, probably in the Fertile Crescent, in the Middle-East. Cheese-making had certainly spread (haha) into Europe by the time of the Roman Empire. By 77 AD, Pliny the Elder claimed that the best cheese was from the city of Nîmes and the Lozère region, both located in Gaul – in other words, modern-day France.
Interestingly, an etymological analysis of the word fromage shows that the word comes from the importance of the fabrication process. In antiquity, the Latin term caseus formaticus was used to refer to “cheese made in a mold”. While the English, Spanish and Germanic languages kept the first word (that became cheese, queso, Käse), the French language kept the second word formaticus, thus emphasizing on the form determined by the mold. Subsequently “forma” became “fourmage” then”fromaige” and finally “fromage” in the 15th century.
Pas la peine d'en faire tout un fromage !
No need to make a big fuss about it!
Il fait tout un fromage d'un petit rien!
He's making a big deal out of very little!
Equivalent in Provence: Pas la peine d'en faire un aïoli!