Spread 1/5 of the spinach mixture along one short side of 1 phyllo stack, leaving 1/2-inch border on both long sides. Fold over border on both long sides, then roll up phyllo starting at one short side. Repeat with remaining phyllo and spinach mixture. Place, seam-sides down, on parchment-covered baking sheets; spray lightly with cooking spray. Use serrated knife to gently score top of each log into 6 pieces.