Fresh grape cake with luscious lemon sauce

11⁄2 cups all-purpose flour;

1 teaspoon baking powder;

1⁄4 teaspoon baking soda;

1 teaspoon kosher salt;

3⁄4 cup plus 2 tablespoons sugar, divided;

8 tablespoons (1 stick) unsalted butter, at room temperature, divided;

3 tablespoons extravirgin olive oil;

2 large eggs, at room temperature;

1 teaspoon finely grated lemon zest;

1 teaspoon finely grated orange zest;

1 teaspoon pure vanilla extract;

1 cup orange muscat wine or other citrusy white dessert wine;

11⁄2 cups red seedless grapes;

Preheat the oven to 400°F. Brush the inside of a 10-inch springform pan with olive oil. Line the bottom of the pan with a round of parchment paper and then brush the parchment with olive oil.
Whisk together the flour, baking powder, baking soda, and salt in a medium bowl.
Whisk together 3⁄4 cup of the sugar, 6 tablespoons of the butter, and the oil in a large bowl until smooth. Whisk in the eggs until smooth. Whisk in the lemon zest, orange zest, and vanilla. Add the flour mixture in thirds, alternating with half of the wine, whisking the batter after each addition just until it is smooth.
Spread the batter into the prepared pan. Sprinkle the grapes over the top of the batter. (The grapes will sink as the cake bakes.)
Bake until the top is just set, about 20 minutes. Dot the top of the cake with the remaining 2 tablespoons of butter, and sprinkle with the remaining 2 tablespoons of sugar. Continue baking until the top of the cake is golden and a tester inserted into the center comes out clean, about 20 minutes more. Cool the cake in the pan on a wire rack for 20 minutes. Release the pan sides, remove the cake, and gently peel away the parchment paper from the bottom.
Serve the cake slightly warm or at room temperature topped with a generous spoonful of Luscious Lemon Sauce