Preheat oven to 425 degrees F.
In a small cup, mix together plant milk and vinegar and set aside.
In a large bowl, add bananas, butter, sour cream, plant milk + vinegar mixture, and vanilla extract and cream together using an electric hand mixer.
In a separate bowl, add baking powder, baking soda, cinnamon, salt, and chocolate chips/chunks, and then sift in flour.
Incorporate wet ingredients into dry ingredients using a wooden spoon or rubber spatula. Make sure to get underneath the batter to check that all dry mixture has been made wet, but DO NOT OVERMIX.
Scoop batter into lined muffin tray (I got 5 jumbo muffins out of this) and place in oven for up to 10 minutes. Reduce heat to 350° F and cook for an additional 18 minutes (more like 12 mins if smaller muffins), until muffins bounce back when pressed.