• Preheat the oven to 425°F (220°C). Grease the muffin pan with non-stick oil spray or line it with paper liners, and set aside.
• If using paper liners, lightly grease them as well.
• Sift flour, cocoa powder, baking powder, baking soda, and salt together and whisk well in a medium bowl.
  2 cups (240g) all-purpose flour, 1 teaspoon baking powder, ½ teaspoon baking soda, ½ teaspoon salt, ½ cup (42g) unsweetened cocoa powder
• Add chocolate chips to the flour mixture, and mix well.
  1 cup (170g) semi-sweet mini or regular chocolate chips
• Add oil, sugar, and sour cream or yogurt to a large mixing bowl. Whisk until everything is well combined and the mixture is smooth.
  ½ cup (120ml) oil, 1 cup (200g) granulated sugar, 1 cup (240g) sour cream or plain yogurt
• Add milk and vanilla. Whisk until everything is well combined and smooth.
  ½ cup (120ml) milk, 1 teaspoon pure vanilla extract
• Fold the dry ingredients into the wet ingredients and gently mix until well combined. But do not overmix. The batter will be thick.
• Divide the batter evenly between the muffin tins. Fill each muffin tin all the way up to the top. I recommend using an ice cream scoop for even, easy distribution of the batter.
• Bake the muffins for 5 minutes at 425°F (220°C), and then, keeping the muffins in the oven, reduce the oven temperature to 350°F (180°C).
• Continue baking for 13-15 minutes or until the cake tester inserted in the center comes out clean.
• Because every oven is different, once you reduce the temperature, keep an eye on it after 12 minutes of baking time.
• Remove the muffins from the oven and let them cool in the pan for 3-4 minutes. Then transfer them onto a cooling rack and let them cool completely before serving.

Storing Suggestions

• Room Temperature: Store in an airtight container for up to 4 days.
• Refrigerator: Keep for up to 1 week in a tightly sealed container.
• Freezer: Freeze in a freezer-safe bag for up to 1 month. Thaw at room temperature or warm slightly in the microwave before serving.