Preheat oven to 350°F (175°C). Grease and flour a 9x5-inch loaf pan, or line with parchment paper. You can also use an 8x4-inch loaf pan and bake muffins alongside.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy.

In a separate bowl or blender, combine the mashed bananas, eggs, sour milk (or buttermilk), salt, and baking soda. Mix until well combined and smooth.

Gradually add the dry ingredients (flour) to the wet ingredients, mixing until just combined. Be careful not to overmix.

Fold in 1.5 cups of the chocolate chips.

Pour the batter into the prepared loaf pan and spread evenly. Sprinkle the remaining chocolate chips over the top.

Bake for 50-60 minutes, or until a toothpick inserted into the center comes out mostly clean (test near the crack).

Let the banana bread cool in the pan for at least 10 minutes before transferring it to a wire rack to cool completely.