- 1 1/2 cups plus 1 tablespoon all-purpose flour, divided
- 1 1/2 teaspoons baking powder
- 1/2 teaspoon baking soda
- 1/4 teaspoon salt
- 1 stick unsalted butter, softened
- 2/3 cup plus 2 tablespoons granulated sugar, divided
- 2 large eggs
- 1 tablespoon grated orange zest
- 2/3 cup Vin Santo or other sweet wine
- 1 1/4 cups seedless red grapes (7 ounces)
- a jumbo/Texas muffin pan with 6 large (6-to 8-oz) cups (see cooks' note, below)
- confectioners sugar
- Preheat oven to 375°F with rack in middle. Generously butter muffin cups and dust with flour, knocking out excess.
- Whisk together 1 1/2 cups flour, baking powder, baking soda, and salt.
- Beat butter with 2/3 cup granulated sugar using an electric mixer at medium speed until light and fluffy. Add eggs 1 at a time, beating well after each addition. Beat in zest.
- Add flour mixture in 2 batches alternately with wine, beginning and ending with flour and mixing until just incorporated.
- Toss grapes with remaining tablespoon flour, then fold into batter.
- Divide batter among muffin cups. Sprinkle with remaining 2 tablespoons granulated sugar. Bake until golden and springy to the touch, 18 to 20 minutes. Cool in pan 5 minutes, then loosen with a knife and remove. Cool to warm, 5 to 10 minutes more.