1. Preheat the oven to 425°F and line a muffin tin with paper liners.
2. In a mixing bowl, whisk together flour, baking powder, baking soda, salt, and a pinch of cinnamon.
3. In another bowl, combine melted butter, oil, granulated sugar, and brown sugar, mixing until well combined.
4. Add eggs one at a time, beating well after each addition.
5. Stir in buttermilk (or Greek yogurt) and vanilla extract.
6. Gradually mix the dry ingredients into the wet ingredients until just combined.
7. Fold in a mixture of mini and regular chocolate chips or chunks.
8. Let the batter rest for 15-60 minutes for a fluffier texture.
9. Fill muffin cups almost to the top with batter.
10. Sprinkle coarse sugar on top for a bakery-style crunch.
11. Bake at 425°F for 5-7 minutes, then reduce the temperature to 350°F and continue baking for 15-18 minutes.
12. Check for doneness by inserting a toothpick into the center; it should come out clean.
13. Remove muffins from the oven and let them cool in the pan for a few minutes before transferring to a wire rack.
14. Serve warm for the best taste and texture.
15. Store leftovers in an airtight container at room temperature for up to 2-3 days.