The blend here is 52% Chardonnay,32% Pinot Meunier, and 16% Pinot Noir, from the 2018 harvest, with tank-aged reserve wine (3%), aged for a minimum of 35 months on the lees.  It's a classic sparkler from these three grapes, with light persistent bubbles, clean and fresh. Its toasty/yeasty notes coupled with a citrus tinge might suggest sourdough. Drinking well now, it has enough acid to rein in the round fruit and support it for a few years yet.