Preheat your oven to 425 degrees (F) and line a 12-cup muffin tin with paper liners.
In a large bowl, whisk together 3 cups of all-purpose flour, 1 cup of granulated sugar, 1/4 cup of light brown sugar, 1 tablespoon of baking powder, 1/2 teaspoon of salt, 1/4 teaspoon of nutmeg, and 1/2 teaspoon of cinnamon.
In a separate large bowl, add 2 large eggs, 1 cup of melted unsalted butter, 1 cup of sour cream, 1/3 cup of milk, 1/2 teaspoon of lemon juice, 2 tablespoons of oil, and 2 teaspoons of vanilla extract. Whisk until everything is well combined.
Fold the wet ingredients into the dry ingredients using a rubber spatula. Stop stirring when you can still see a hint of the dry ingredients.
Fold in 2 cups of semi-sweet chocolate chips.
Divide the batter evenly among the prepared muffin pan, filling each mold to the top.
Place the muffin pan in the preheated oven and bake at 425 degrees for 8 minutes. Then, reduce to 375 degrees and bake for an additional 14 minutes.
Cool the muffins in the pan on a wire cooling rack for 15 minutes. Then, carefully remove the muffins from the pan.
