Nutella-Banana Coffee Cake

CAKE:
1 c. unsalted butter
3 ¾ c. flour
2 c. sugar
1 T. baking powder
1 ½ t. salt
¼ t. baking soda
1 c. buttermilk
4 large eggs, room temp
¼ c. sour cream
2 t. vanilla
FILLING:
2 small ripe bananas, peeled and thinly sliced
½ c. Nutella
¼ c. packed light brown sugar
TOPPING:
4 T. butter
1 c. flour
3 T. sugar
2 T. packed light brown sugar
1 ¼ t. ground ginger
1 t. ground cinnamon
1. Preheat oven 350. Grease 13×9” baking pan with softened butter and dust pan with flour.
2. In saucepan over low heat, melt butter and set aside to cool.
3. In large bowl, whisk together flour, sugar, baking powder, salt and baking soda.
4. In separate bowl, whisk together buttermilk, eggs, sour cream, vanilla and melted butter, until very smooth.