Preheat the oven to 350°F (180°C).
Line 12 regular muffin tins with paper cups.
Beat ¾ cup vegetable oil with ½ cup light brown sugar and ¼ cup white sugar for 1 minute in a medium bowl. You can use a whisk or an electric mixer at low speed.
Add 2 eggs one by one, beating until fully incorporated, but don’t overmix.
Add the rest of the wet ingredients: ¾ cup sweet potato puree, ½ teaspoon vanilla extract, and 1 teaspoon orange zest. Integrate until smooth.
In a large bowl, sift 2 cups all-purpose flour, 2 teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon salt, and ½ teaspoon ground cinnamon or spices of choice. You can have them measured and sift as you add them, or have them already sifted in another bowl.
Add the dry ingredients to the sweet potato mixture in 2 parts, integrating well but not beating, just stirring. I do it by hand with a spatula.
Fill the paper liners up to ¾ of their capacity. But do not fill more than three quarters, so they don’t overflow while baking.
In a small bowl, mix 1 tablespoon brown sugar and ¼ teaspoon ground cinnamon together for topping. Sprinkle on top of the muffins.
Bake for about 25 minutes, or until a cake tester or toothpick comes out dry. The top of the muffins will be slightly cracked and golden brown. Don’t overbake.
Let cool on a wire rack.
Store covered at room temperature for two days and then refrigerate or freeze, covered or wrapped. Warm lightly in the oven before eating.