Preheat oven to 375 degrees F (190 degrees C). Grease a doughnut pan with about 1 teaspoon vegetable oil.

Sift flour, baking powder, cinnamon, ginger, nutmeg, allspice, salt, and cloves together in a large bowl; stir brown sugar into flour mixture until well mixed.

Whisk pumpkin puree, 1/3 cup vegetable oil, 1/3 cup maple syrup, buttermilk, and egg together in a separate bowl until smooth. Stir pumpkin mixture into flour mixture until batter is just combined. Refrigerate batter for flavors to blend, 20 to 40 minutes.

Scoop about 1/4 cup batter into each doughnut well.

Bake in the preheated oven until a toothpick inserted in the center of a doughnut comes out clean, 9 to 13 minutes. Cool doughnut completely in pan. Loosen edges of each doughnut with a small offset spatula or knife and transfer to wire rack.

Whisk confectioners' sugar and 3 tablespoons maple syrup together in a small bowl until glaze is smooth.

Press doughnuts facedown into glaze to cover the top completely. Place doughnuts on a wire rack for glaze to set, 2 to 3 minutes. Sprinkle pumpkin seeds over glaze.