With its rich, mushroom-studded filling tucked under a layer of soft mashed sweet potato, it has all the hallmarks of a good shepherd's pie, but it's completely vegan — and includes a secret ingredient that adds body and creaminess to the filling, without any cream. Authentic shepherd's pie is a comfort food classic, but there's no room in my diet or grocery budget for a heavy dish of ground lamb or beef and buttery potatoes, except as an occasional treat. Lentils, mushrooms, and sweet potatoes, roasted until creamy-soft, need just a little salt and pepper to be a flavorful topping. This recipe uses one unusual ingredient: steel cut oats! The dry oats — cooked and drained with the lentils — release just enough starch to bind the filling into a creamy, mushroomy mass, rather than a loose scattering of lentils and vegetables. The oats also add a texture somewhat like ground meat, but they aren't noticeable unless you know to look for them, so your guests will have no idea their dinner includes a nutritious breakfast staple. Note: STEAMING the sweet potatoes saves you an HOUR off this recipe plus retains vital nutrients!