Moist Spiced Banana Cake with Creamy Frosting

Ingredients

• 2 cups all-purpose flour
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 1 teaspoon ground cinnamon
• 1/2 teaspoon ground nutmeg
• 1/2 teaspoon ground allspice
• 1/2 teaspoon salt
• 1/2 cup unsalted butter, softened
• 1 cup granulated sugar
• 1/2 cup packed light brown sugar
• 2 large eggs
• 1 teaspoon vanilla extract
• 1 1/2 cups mashed ripe bananas (about 3 large bananas)
• 1/2 cup sour cream
• 1/2 cup chopped walnuts (optional)
• Creamy Frosting:
• 8 oz cream cheese, softened
• 4 cups powdered sugar
• 2 tablespoons heavy cream