Step 1

Preheat oven to 350° F. Grease and flour 2 (8-inch) cake pans. Cut 2 circles of parchment paper to fit the bottoms of the pans, then press them in (this will make it easier to remove the cake from the pan)

Step 2

In a medium bowl, whisk together, flour, baking soda, and cinnamon and set aside. In a mixer fitted with a whisk attachment (or using a hand mixer), cream the butter until smooth. Add sugars and eggs and mix until fluffy, then add mashed bananas and vanilla.

Step 3

Add half the dry ingredients and half the sour milk and mix just until combined. Repeat with remaining dry ingredients and milk.

Step 4

Fold in chocolate chips. Pour batter evenly into prepared pans and bake for 30-40 minutes. Let cakes cool in the pans 5-10 minutes. Turn out onto wire racks and let cool completely before frosting.

Step 5

Cream shortening and butter with an electric mixer. Add ice cream topping, salt and vanilla. Gradually add sugar, one cup at a time, beating well on medium speed. Stop to scrape sides and bottom of bowl as needed.

Step 6

When all sugar has been mixed in, icing will appear dry. Add milk 1 tablespoon at a time and beat at medium speed until light and fluffy.