Rob Waddell, a former recipe developer, brings a technician's diligence to his short line of custards, which he bakes in four-ounce bell jars and sells at local farmers' markets. At a cool room temperature, his vanilla custard has the weight and smoothness of softened butter. Ask him to brûlée any flavor, and it takes him four or five applications of pale-beige organic sugar, each torch-blasted to glassy amber. The resulting crust is as thin and brittle as birdbath ice in a San Francisco backyard.