You have a rare chance to watch a baker's talent take an evolutionary leap.

At the month-old M.H. Bread & Butter in San Anselmo, you can see the evidence of owner Nathan Yanko's nine years of baking at Tartine.

It shows up in the rugged shells of the walnut ($9) and whole-wheat rye loaves ($5 for a small; $8 for a large), and in the gossamer weave of dough and air in his sourdough baguettes ($4).

But you can also see his creativity unfurl.

Yanko and Devon Crosby-Helms, his wife and business partner, say they're introducing new items every day. They range from tangy, buttery lemon-poppy-seed cookies (50 cents) and savory chorizo-cheese scones ($4) in the pastry case to Arielle Segal's full lunch and dinner menus, which début this week.

The mix of flours and grains in Yanko's breads is evolving too, as he develops his own style.

Two new breads we were excited to discover: a tart, crusty sprouted-grain sandwich loaf ($12) that--heresy!--may outshine Outerlands' levain, and a long, gnarled tordu ($4). When we tore off a hunk, its twisted crust broke off in flakes, and spelt flour gave the airy crumb a soft nuttiness.