Banana Swirl Coffee Cake

Ingredients

• 1/2 cup walnuts
• 1/2 cup flour
• 1/2 cup brown sugar, packed
• 1/2 tablespoon cinnamon
• 4 tablespoons cold butter, cubed
• 2 1/4 cups all-purpose flour
• 1 1/4 teaspoons baking powder
• 1 1/4 teaspoons baking soda
• 1 teaspoon salt
• 1 teaspoon cinnamon
• 1/2 cup butter, softened
• 1 1/2 cups sugar
• 2 large eggs, at room temperature
• 1 cup bananas, mashed
• 1 tablespoon vanilla extract
• 1 1/4 cups sour cream, not nonfat, at room temperature
• 1/2 cup semi-sweet chocolate chips, optional
• 1/2 cup walnuts, chopped, optional
• 8 ounces cream cheese, softened
• 1/4 cup reserved batter from the banana cake
• 1/4 cup sugar
• 1 teaspoon vanilla extract
• 1 cup powdered sugar
• 2 tablespoons milk
• mini chocolate chips, to taste