Ingredients

• Cooking spray

• 1 1/2 cups all-purpose flour (about 6 3/8 ounces)

• 1/2 cup unsweetened cocoa

• 1 teaspoon baking soda

• 1 teaspoon kosher salt

• 1/2 cup unsalted butter, melted

• 1/2 cup packed light brown sugar

• 1/2 cup granulated sugar

• 1 1/2 cups mashed overripe banana (from 3 to 4 large bananas)

• 1/2 cup sour cream or plain whole-milk Greek yogurt

• 2 large eggs, at room temperature

• 2 teaspoons vanilla extract

• 1 cup granulated sugar

• 1/4 cup water

• 1 tablespoon light corn syrup

• 3/4 cup heavy cream

• 1/2 cup extra-crunchy peanut butter

• 1 tablespoon vanilla extract

• 1/2 teaspoon kosher salt