Preheat oven to 350°F. Spray an 8x4 or 9x5 loaf pan with nonstick cooking spray (use the kind with flour for best results).
Stir together the pumpkin puree, 1/4 cup granulated sugar, vanilla, pumpkin pie spice, and egg. Set aside.
Open the can of biscuits and slice each in half horizontally. Stir together remaining 1/4 cup granulated sugar and 1 teaspoon cinnamon in a small bowl. Coat each slice of raw biscuit dough with the cinnamon sugar mixture.
Lay one slice of dough flat. Spread some pumpkin mixture on top, then place another biscuit piece on top. Add more pumpkin mixture and continue stacking, spreading, and layering until you’re out of biscuits and pumpkin. Place carefully into the pan.
Bake for about 30-40 minutes, or until the top is golden and the center is cooked through. Cool before glazing. Note: the center shouldn't be raw, but will be moist and gooey. If the top starts to brown too fast, cover with foil and reduce oven temperature to 325°F.
To make the glaze: whisk the powdered sugar, cinnamon, and heavy whipping cream until a smooth sauce forms. Drizzle over loaf, pull apart, and serve.
Store loosely covered for up to 2 days.