Preheat your oven to 350°F (177°C). Prepare your donut pan(s) by greasing them with nonstick spray and setting them aside.

In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and pumpkin pie spice until they are evenly combined. Set this mixture aside.

In another medium bowl, whisk together the oil, brown sugar, eggs, pumpkin puree, milk, and vanilla extract until thoroughly combined.

Gently pour the wet ingredients into the dry ingredients. Use a whisk to combine them just until you no longer see any flour pockets. Avoid over-mixing to maintain a tender texture.

Spoon the batter into the donut cavities directly or use a large zipped-top bag for easier pouring. Cut a corner off the bag and pipe the batter into each cavity, filling them about halfway.

Place the pan in the preheated oven and bake for 10–11 minutes, or until the edges and tops are lightly browned. A good test is to poke the tops; if they bounce back, they’re ready!

Let the donuts cool in the pan for about 2 minutes, then transfer them to a cooling rack. If you have more batter, re-grease the pan and bake the remaining donuts.

For mini donuts, adjust the bake time to 8–9 minutes.

In a medium saucepan over medium heat, combine the brown sugar, milk, and butter. Stir until the butter melts and the mixture is smooth, then bring it to a simmer for about 1 minute.

Remove from heat, whisk in vanilla extract and sifted confectioners’ sugar until smooth. Taste and adjust with a pinch of salt as needed. Allow to cool slightly until thickened.

Dip the tops of the warm pumpkin donuts into the slightly cooled icing. If the icing thickens too much, add a little more milk or warm it slightly to restore the desired consistency.

Place the dipped donuts on a cooling rack over a baking sheet to catch any excess icing. Top with chopped walnuts or any other desired toppings.

Cover any leftover donuts tightly and store them at room temperature for up to 1–2 days, or in the refrigerator for up to 1 week.