Individual Grape and Vin Santo Cakes

INGREDIENTS

• 1 1/2 cups plus 1 tablespoon all-purpose flour, divided
• 1 1/4 cups seedless red grapes (7 ounces)
• 2 large eggs
• 1 tablespoon grated orange zest
• 1/4 teaspoon salt
• confectioners sugar
• 2/3 cup Vin Santo or other sweet wine
• 1/2 teaspoon baking soda
• 2/3 cup plus 2 tablespoons granulated sugar, divided
• 1 stick unsalted butter, softened
• 1 1/2 teaspoons baking powder