1/2 cup (1 stick) unsalted butter, melted, plus more for the pan
1/2 cup all-purpose flour, spooned and leveled
1/3 cup instant grits
3/4 teaspoon baking powder
1 teaspoon fine salt
2 large eggs
3/4 cup sugar
3 tablespoons bourbon
1 teaspoon pure vanilla extract
4 apples, chopped
Heat oven to 350° F.
Butter an 8-inch springform pan and set on a rimmed baking sheet.
Whisk together the flour, grits, baking powder, and salt in a small bowl; set aside.
In a separate bowl, whisk the eggs until foamy. Add the sugar, bourbon, and vanilla and whisk to combine. Whisk in the flour mixture and butter in alternate additions, beginning and ending with the flour mixture. Mix until just combined. Fold in the apples. (The batter will be very apple-heavy.) Transfer the batter to the prepared pan.
Bake until a toothpick inserted in the center comes out clean and the cake is golden brown, 60 to 70 minutes. Cool the cake in the pan for 10 minutes.
Run an offset spatula or butter knife around the edge of the pan to loosen, then remove the sides of the pan.