Moist Double Chocolate Chip Muffins

Ingredients;
2 large eggs
3/4 cup sour cream (170g)
1/2 cup milk (120ml)
2 teaspoons vanilla extract (10ml)
1-3/4 cups all-purpose flour (210g)
2/3 cup unsweetened cocoa powder (60g)
1 cup granulated sugar (200g)
1 1/2 teaspoons baking powder
1 teaspoon baking soda
3/4 teaspoon salt
2 cups semi-sweet chocolate chips
1/2 cup vegetable oil (120ml)