Plum Upside-Down Cake – Duke's Mayo

Ingredients

• 1/4 cup salted butter
• 1/2 cup firmly packed light brown sugar
• 1/4 teaspoon ground cinnamon
• 3 black or red plums, pitted and thinly sliced
• 2 cups all-purpose flour
• 1 teaspoon baking powder
• 1/4 teaspoon salt
• 1 cup granulated sugar
• 1 cup Duke’s Mayonnaise
• 3 large eggs
• 1/2 cup whole milk
• 1 teaspoon vanilla extract
• 1/2 teaspoon almost extract