The French wine labelling laws love to confuse us, since winemakers worldwide use the French as the bar to measure against, their labelling terms have infiltrated the globe, thus confusing us all no matter where we live.
This French term, Blanc de Blancs translates as 'white from whites'. This refers to a sparkling wine made from white or more specifically, green grapes. This term was created to denote Champagne's that were made from the white grapes of the region; notably Chardonnay.
Even though a there is a smattering of other white grapes that are permitted in Champagne (Arbanne, Petit Meslier, Pinot Blanc and Fromenteau/Pinto Gris), Chardonnay is the lead by far in both vineyard plantings (30% of all plantings in Champagne) and is unanimously deemed the quality white grape. Therefore when you see the term; Blanc de Blancs on a bottle of Champagne, safe to assume it is 100% Chardonnay.
As a style of Champagne, Blanc de Blancs have substantially risen in popularity over the years, with the norm for a Champagne house or grower to produce this style, most often in a vintage style (where the grapes are from one vintage only rather than a 'non-vintage' blend of years).
Some notable Champagne Blanc de Blancs are;
Pierre Gimonnet (a grower with an entirely Blanc de Blancs range)
Salon 'Le Mesnil'
As Champagne is the pinnacle of sparkling wine production, producers within other regions of the world that focus on sparkling wine use Champagne and its methods, labelling terms and styles. Most regions in the world will adhere to the 100% Chardonnay Champagne rule when producing a Blanc de Blancs however some regions in the world have leaned into their own uniqwue style of sparkling wine and have notable differences. Spanish Cava for example will often have Chardonnay accompanied (or missing from the blend completely) by Macabeo, Parellada and Xarel.lo. Italian Franciacorta however will base their Blanc de Blancs on Chardonnay but often have Pinot Blanc in the blend as well, technically more ion common with Champagne yet both these styles are notably different to those of the same name from Champagne itself.
In the New World (everywhere outside of Europe) of winemaking, any producer that is serious about 'Methode Traditionelle' a.k.a. the Champagne method of sparkling wine, they will base their Blanc de Blancs on Chardonnay only. California, New Zealand, Adelaide Hills and Tasmania are all regions that have seriously fantastic sparkling wine producers and many have exceptional Blanc de Blancs options. Notably;