Heat the oven to 350°F and make sure there’s a rack close to the middle. (Use the conventional, not convection setting to avoid scattering the oats into the oven.) Spread the oats evenly into a large rimmed baking sheet. They should be no more than 1/2 inch thick; if thicker, transfer some of the oats to another rimmed baking sheet and spread them the same way.
Put the pan in the oven and bake for 15 minutes, then toss with a stiff spatula, spreading the oats evenly into the bottom of the pan again. Return the oats to the oven and repeat every 10 minutes until they’re as dark and crisp as you’d like them. (Be aware that they will crisp more as they cool.) Total baking time will vary depending on what part of your oven is the hottest and how dark you want them.
Let the oats cool in the pan (or pans), tossing a couple times so they cool evenly. Transfer them to an airtight container, where they will keep in the pantry for a couple months.
– Recipe developed by The Bittman Project for Bob’s Red Mill