Preheat oven to 300°F (150°C).

For cake: In a large bowl, whisk together pumpkin, brown sugar, granulated sugar, sour cream, oil, eggs, espresso powder, and vanilla.

In a medium bowl, whisk together flour, pie spice, salt, baking powder, pepper, and baking soda. Gradually whisk flour mixture into pumpkin mixture until just combined.

Spray a 10-cup fluted tube pan with baking spray with flour. Using a pastry brush, brush spray into nooks of pan. Spoon batter into prepared pan. Tap pan on a kitchen towel-lined counter several times to settle batter and release any air bubbles.

Bake until a wooden pick inserted near center comes out clean and an instant-read thermometer inserted near center registers 200°F (93°C) to 205°F (96°C), 1 hour to 1 hour and 15 minutes. Let cool in pan for 10 minutes. Invert cake onto a wire rack, and let cool completely.

For glaze: In a small bowl, stir together confectioners’ sugar, sour cream, 2 teaspoons (10 grams) water, vanilla, and salt until smooth and well combined; spoon onto cooled cake. Store in an airtight container for up to 3 days.