How to bake the Perfect Chocolate Puddle Cookie

After developing a not-regrettable addiction to the outrageously large cookies from San Francisco’s b. Patisserie, I found myself lying awake at night tweaking recipes in my head (does no one else do this?) to replicate their inimitable result — crispy edges, chewy centers, tempting pools of dark chocolate rippling on the surface and, to my complete befuddlement, a thin vein of chocolate going right through the middle.

After months of work, testing methods and tasting the results in my kitchen (tough job...