Plum Upside-Down Cake Recipe

Ingredients

• 2 tablespoons butter
• 2 tablespoons brown sugar, or to taste
• 1 1/2 tablespoons blanched almond flour
• 3 plums, pitted and sliced
• 1/2 cup unsalted butter, softened
• 1/2 cup white sugar
• 1 egg, at room temperature
• 3/4 teaspoon vanilla extract, or to taste
• 1 1/2 cups all-purpose flour
• 2 teaspoons baking powder
• 1/2 teaspoon salt
• 1/2 teaspoon ground cinnamon
• 1 cup milk, at room temperature