Step 1: Preheat your oven to 350°F (175°C).
Step 2: Grease your 9x5 inch loaf pan with butter or non-stick spray.
Step 3: In a large mixing bowl, beat the butter and sugar until light and fluffy (about 3-5 minutes).
Step 4: Add the eggs one at a time, mixing well after each addition, then fold in the bananas and vanilla.
Step 5: In a separate bowl, whisk together the flour and baking soda, then gradually add to the wet ingredients, alternating with sour cream.
Step 6: Gently fold in the chocolate chips.
Step 7: Transfer the batter to the prepared loaf pan, smoothing the top.
Step 8: Bake for 60-70 minutes, or until a toothpick inserted comes out clean.
Step 9: Let it cool in the pan for 10 minutes before transferring to a wire rack to cool completely.