Cuvée 3A is a blend of three Grand Cru terroirs of remarkable purity. Avize, in the heart of the Côte des Blancs, rests on the purest chalk in Champagne, composed of fossilised belemnites dating back millions of years, which impart freshness, minerality and finesse to the Chardonnay. The grapes come from vines over 50 years old, vinified in 225-litre oak barrels. Aÿ, situated where the Marne Valley meets the Montagne de Reims, offers full southern exposure and irregular topography that allow Pinot Noir to express aromas of ripe fruit, combining power and finesse. Ambonnay, on the Montagne de Reims, features a vast forested plateau planted on chalky soils. The vines, planted in the 1950s, yield low but deliver greater maturity and concentration.

Champagne De Sousa cultivates its 10-hectare vineyard under organic agriculture (AB certified since 2010) and biodynamic principles (Demeter certified since 2013). Part of the vineyard is worked with horses to avoid soil compaction. Harvesting is manual, vinified according to the traditional Champagne method with indigenous yeasts. Cuvée 3A is aged half in stainless steel tanks and half in 225-litre oak barrels, without filtration or fining. The blend incorporates 20 to 30% reserve wines from a perpetual reserve started in 2014, stored in an egg-shaped vat. Dosage is low, in Extra Brut style (approximately 5 g/l), to preserve purity of expression. Ageing on lees lasts a minimum of 24 months in the chalk cellars at a constant temperature of 10°C. Riddling is carried out manually.