In a bowl whisk together flour, sugar, baking powder, baking soda and salt. Add 1 1/2 cups of chocolate chips and toss to coat. Set aside.
In a separate bowl whisk together eggs, milk, oil, melted butter and vanilla until fully combined.
Slowly add flour mixture, stirring until just combined. The batter will be very thick! Let it rest for 15 minutes while your oven preheats.
Preheat oven to 425º F.
Line a 12 cup muffin tin with 6 liners, you want to alternate every other spot to give them enough space to really rise up and not crowd each other.
Fill each liner with a rounded 1/2 cup of batter and sprinkle the reserved chocolate chips over the top.
Bake muffins for 7 minutes, reduce oven to 350º F. and cook for 14-16 more minutes; or until a tester comes out clean. Do not open the oven door when you reduce the heat.
Remove from oven and cool on a wire rack for 5 minutes before removing from the pan.