Preheat oven to 350. Grease a bread pan with non stick spray. In a large mixing bow, on low speed, combine butter and sugar until creamy and fluffy. Meanwhile, in a microwave safe bowl, melt the chocolate chips and set aside. To the butter mixture, add the eggs, mashed bananas, and sour cream. Mix until completely combines. On low speed, slowly add the flour, baking soda, salt, and cinnamon just until all is incorporated. Pour half of the batter in the greased bread pan. Mix the remaining batter with the melted chocolate. Pour the chocolate batter mixture over the plain batter. With a fork, gently swirl the chocolate into the plain batter. Bake for 1 hour to 1 hour 20 minutes or until knife inserted in center comes out clean. Let cool for 5 minutes in pan, then remove to cool on a cooling rack. For Ganache: In a microwave safe bowl, combine chocolate chips and heavy cream. Microwave for 30 seconds at a time, stirring after each time, until smooth. Pour ganache over bread.