Preheat your oven to 425°F or 218°C. Grease your jumbo muffin pan well with nonstick spray, butter, or muffin liners.
Whisk flour, baking soda, baking powder, cinnamon, salt, and nutmeg in a bowl. Set aside for a second.
In another bowl, whisk the unsalted butter, sugar, oil, and eggs. Then, mix the milk, sour cream, and vanilla until the mixture turns pale yellow.
Pour that wet mixture into the dry ingredients (from Step 1) and gently fold them with your spoon or spatula. Don't go overboard. Once everything's combined, fold in chocolate chips.
Divide your batter evenly between the muffin cups, filling them about ¾ full. Optional: sprinkle some coarse sugar before you pop them in the oven.
Bake them for 5-7 minutes, then lower the heat to 350°F (or 177°C) and wait another 25-27 minutes. You'll know they're done when the tops become golden brown, and a toothpick stuck in the middle comes out mostly clean.
Let them cool for 8-10 minutes in the pan. Enjoy!