Preheat oven to 375°F. Line a muffin pan with cupcake liners. Line a second muffin pan with 5 cupcake liners. Set aside. Note: If you do not have a second muffin pan, be sure to let your pan cool for 10-15 minutes before baking the other 5 muffins. 

In a medium-sized bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, use a hand mixer or stand mixer to cream the butter on medium speed for 2 minutes. Add the sugar and cream on medium speed for 2 minutes. Add the eggs, beating on low speed until just combined in between each addition. Add the vanilla, and mix until just combined.

Add 1/3 of the flour mixture into the butter mixture and mix on low speed until mostly combined. Add 1/2 of the buttermilk and 1/2 of the Greek yogurt, and mix until mostly combined. Add another 1/3 of the flour mixture, again mixing until mostly combined. Add the rest of the buttermilk and Greek yogurt and mix until mostly combined. Finally, use a spatula to gently mix in the rest of the flour mixture until just combined. 

Using a spatula, fold the mini chocolate chips into the batter. Scoop the muffin batter into the tins, about 2/3 full. Bake at 375°F for 15 minutes, or until golden brown.