An oniony tarte Tatin is one-pan heaven

Here's an ease-into-fall appetizer that will make you look like a culinary rock star — even with entry-level skills and not much time to spend in the kitchen. You build the dish from the bottom up, starting the caramelization of onions on the stove top. Pinches of pungent cheese nestle into the background of sweet, meaty walnuts and mushrooms under a blanket of puff pastry that becomes the crisped, golden base once you invert the tart for serving.