This cloudlike version of pumpkin pie uses earthy tahini for extra nutty flavor. The trick to keeping it so light is mixing the pumpkin-tahini base with whipped cream in two additions: The first half ensures that the mixture is well combined, while the second half is ever so gently folded in to maintain its airiness. Lining the pan with sesame seeds gives additional texture to the cookie crust, helping it stay firm even when the pie is made ahead. We recommend topping with dried seasonal fruit just before serving. Pop any leftovers into the freezer: This pie is equally enjoyable as a frozen treat.