Preheat your oven to 350°F (175°C). This is a crucial step to ensure even baking.
Grease a donut pan with non-stick cooking spray or use a silicone mold for easy removal.
In a large bowl, whisk together the gluten-free flour blend, baking powder, cinnamon, and salt until well combined.
In another bowl, mix the pumpkin puree, brown sugar, eggs, and vanilla extract until smooth.
Gently fold the dry mixture into the wet mix until just combined. Avoid overmixing, as this can lead to dense donuts.
Use a piping bag or a spoon to fill the donut cavities about ¾ full to allow room for rising.
Bake in the preheated oven for approximately 15-18 minutes, or until a toothpick inserted into the center comes out clean.
Allow the donuts to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.
For a delicious finish, mix powdered sugar with a splash of milk or water until smooth, then glaze the cooled donuts.