Freeze the pie. Place the chilled pumpkin pie, uncovered, on a flat freezer shelf for 40–50 minutes, until firm to a fingertip press but not frozen solid.
Warm the cutter. Dip the cutting edge of a 1½-inch straight-sided cutter in hot water and wipe it dry.
Cut the bites. Press the cutter straight down through the filling and crust until it meets the board. Do not twist. Lift straight up. Work around the outer rim first, then the center, leaving ¼ inch between cuts.
Release. If the bite sticks inside the cutter, invert it and press gently on the crust side with your thumb so it drops out top-up.
Repeat. Re-dip and dry the cutter every 3–4 cuts, and any time a bite sticks. You should get 10–12 bites.
Chill again. Transfer the bites to a shallow airtight container in a single layer, not touching. Refrigerate at least 20 minutes, or up to 2 days.
Top and serve. Just before serving, top each bite with whipped cream. Garnish with a dusting of cinnamon or a single toasted pecan half. Serve cold.