Preheat the oven to 425 and prepare a giant muffin tin with muffin liners. Set to the side.
In a medium-sized bowl, combine the flour, baking powder, baking soda, and salt. Set to the side.
In a large bowl, whisk the melted butter, oil, sugar, and eggs. Once fully combined, add the sour cream, milk, and vanilla.
Add the dry ingredients to the wet ingreidents and whisk to combine. Once the mixture is smooth, fold in the chocolate chips.
Pour the batter into the muffin tin. Fill the muffin tin cups about ⅔rds of the way full. You want the batter to almost be to the top.
Place the muffin tin in the oven and bake at 425 for 5 minutes. After 5 minutes, lower the temperature of the oven to 350 and continue to bake for 25-30 minutes.
While the muffins are baking, make the glaze. In a large bowl, combine the powdered sugar, boiling water, heavy cream, corn syrup, vanilla, and salt. Use a whisk to break up the powdered sugar and mix until smooth. Split the icing in half and add the cocoa powder to one half to make it a chocolate glaze.
When the muffins are fully cool, add the glaze. Glaze half of the muffins with the white base using an offset spatula or a spoon. Let the cookies sit for about 15 minutes in the fridge before frosting the other side. Frost the other side with the chocolate glaze when ready.
When the muffins are fully frosted, place them back in the fridge to set for about an hour. Don't rush this process, as this will keep their crisp shine and won't allow for the icing to easily smudge.
