Bread & Butter is a reference to the craft of winemaking.
Bread = Oak. Butter = Malolactic Fermentation.
The type of oak, origin, producer, level of toast, time on oak, and racking all play a vital role in developing bread-like flavors and texture of the wine. Butter characters come from malolactic fermentation. The conversion of malic acid to lactic acid produces rich, buttery flavors and changes the texture of the wine to be more creamy and soft. These factors work together to best compliment the complexity of fruit and expression of terroir produced in the vineyard.