Preheat oven to 425 degrees F. Line 12 cup muffin tin with paper liners. In a mixing bowl whisk together flour, baking powder, baking soda and salt for 20 seconds, set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment whip together butter, 1 Tbsp vegetable oil and sugar until pale and fluffy. Mix in remaining 3 Tbsp vegetable oil.
Blend in eggs one at a time adding in vanilla with second egg. In a 2-cup liquid measuring cup measure out milk then add sour cream and whisk to blend.
Remove mixing bowl from stand mixer and add 1/3 of the flour mixture and fold until nearly combined, then add 1/2 of the milk mixture and fold until nearly combined, repeat process once more with flour and milk mixture.
Add in last 1/3 of the flour mixture and fold until nearly combined then add in chocolate chips (you can set aside about 2 tbsp to sprinkle over the tops before baking so more show through if desired) and fold until just combined.
Divide batter among prepared muffin cups filling each slightly mounded full.
Bake in preheated oven 8 minutes then reduce oven temperature to 400 degrees and continue to bake until toothpick inserted into center comes out clean, about 10 - 11 minutes longer (they should be nicely domed and edges of cupcakes will likely just be slightly touching).
Transfer muffins to a wire rack and let cool (I highly recommend trying at least one while still warm!). Store in an airtight container at room temperature.
If you don't have mini chocolate chips, regular can be substituted.