Preheat oven to 350°F. Spray a 9- x 5-inch loaf pan with cooking spray and line with parchment paper, leaving overhang on 2 sides.
Whisk flour, hemp hearts, pumpkin-pie spice, baking powder, salt, baking soda, cinnamon and nutmeg in a medium bowl.
Whisk eggs, granulated sugar and coconut sugar in a large bowl. Whisk in pumpkin purée, oil, and vanilla. Stir flour mixture into pumpkin mixture just until combined. Pour into loaf pan and smooth top.
Bake until golden brown and a skewer inserted in centre comes out clean, 55 minutes to 1 hour. Cool on a rack for 10 minutes, then remove from pan and cool completely on the rack.