Spread potato mixture evenly on the bottom of a lightly greased 8"x8"x2" baking dish. Cover with a layer of spinach. Crumble feta over spinach and spread shredded turkey evenly over feta. Spoon dollops of stuffing over the cheese and press down lightly. Pour gravy over stuffing. Cover with 3 phyllo sheets, brushing with sage butter between sheets. Always keep a damp towel over remaining phyllo dough to keep pliable. Gently cover phyllo with onions and sprinkle bacon and sage crumbles evenly over the top. Top with grated Gruyère and cover with remaining 3 sheets phyllo, brushing olive oil between each sheet and on the top. Dust with powdered sugar and pumpkin pie spice, and sprinkle with almonds.
Bake for 35 minutes, until dough is lightly browned and flaky. Let cool for 10 minutes before serving.
Phyllo dough should be thawed and room temp.