Preheat the oven to 425°F.

Line the cavities of a 12-cavity muffin pan with muffin/cupcake liners.

Place the canola oil, brown sugar, granulated sugar, vanilla, eggs, pumpkin puree, and milk in a large mixing bowl. Whisk vigorously until smooth and combined.

Add the flour, pumpkin pie spice, baking powder, baking soda, and salt to the bowl. Continue whisking until the mixture is just combined. Do not over-mix.

Fold in the walnuts, mixing until they are evenly distributed in the batter.

Scoop an equal portion of batter into each muffin liner.

Bake the muffins on middle rack of oven for 5 minutes.

Reduce oven temperature to 350°F. Continue baking until a toothpick inserted in the center of a muffin comes out clean, 14-16 minutes.

Check to see that muffins are done. Remove from oven or add time as needed.

Allow the muffins to cool in the pan for 5 minutes before removing and serving. Store leftovers in an airtight container at room temperature for 2 days, or refrigerate for 3 days.