Lemon Plum Cake

INGREDIENTS

• 1 1/2 cups all-purpose flour
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 1 tablespoon cinnamon
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• 3/4 cup unsalted butter, softened
• 1/2 cup packed brown sugar
• 1/2 cup white sugar
• 3 eggs
• 1 tablespoon vanilla extract
• 2 1/2 teaspoons finely grated lemon zest
• 1/2 cup plain yogurt
• 3 plums, pitted and cut into eighths
• 2 tablespoons all-purpose flour
• 1 teaspoon confectioners' sugar