Lionel Vatinet's Stuffed Baguette

French master baker Lionel Vatinet has taken the symbol of traditional French boulangeries–the baguette–and done something unspeakably American to it: He stuffs it.

Vatinet, who moved to the States in 1991 after years of traveling and consulting, bakes his baguettes with delicious stuffings like tomato, basil and mozzarella and sliced ham with Gruyère.

The Franco-calzone mash-up is a seasonal staple at Vatinet's quiet Cary, North Carolina bakery, La Farm: "It's not super French, but not super American either. It's the combination of traditional baking with the creativity of what America brought to me."

After more than 20 years in the business, Vatinet–one of the best bakers you've never heard of–has written his first book, A Passion for Bread ($35), out next month. He stopped by our Test Kitchen to make one of his favorite stuffed baguettes, filled with Gruyère, thyme and roasted cremini mushrooms splashed with soy and balsamic (see the recipe).

Follow Lionel Vatinet's lead and stuff your baguette.

We were blown away by his fluid kneading technique, a process of pinching the loose wet dough repeatedly between the thumb and forefinger–kind of like making an "OK" sign over and over again.

Vatinet says he's never forgotten the first lesson of the dough he learned as a young apprentice: "You need to be firm but gentle. It's something difficult to describe, but it was magical for me."