Chef John's Sweet Potato Muffins - Chefwiz

Ingredients

• Non-stick cooking spray
• 2 cups all-purpose flour
• 2 teaspoons baking powder
• 2 teaspoons cinnamon
• 1 teaspoon kosher salt
• 1 teaspoon baking soda
• ½ teaspoon ground ginger
• 1 pinch freshly grated nutmeg
• 4 large eggs
• 1 ½ cups white sugar
• ½ cup light brown sugar
• 1 cup vegetable oil
• ¼ cup melted butter
• 2 cups mashed sweet potato (yams)
• 1 cup chopped pecans (, plus additional for topping)
• 2 teaspoons demerara sugar for topping