Preheat oven to 375 degrees.
Measure out all dry ingredients (flour, sugar, baking powder, baking soda) into a large bowl.
In a small bowl, mix together egg, oil, vanilla and yogurt (or sour cream).
Add banana and stir.
Add wet ingredients to dry ingredients. Add chocolate chips and gently mix (don’t over mix because muffins will be too tough).
Put muffin papers in muffin tin or use a Stoneware Muffin Pan.
Put ¼ cup of muffin batter into muffin papers.
Bake for approximately 15 minutes or until toothpick inserted comes out clean.
Can use low-fat plain yogurt or low-fat sour cream instead of Greek yogurt.