Fill a large Dutch oven with 1 1/2 inches oil and heat to 350°F. Set a cooling rack on a rimmed baking sheet. Combine granulated sugar and 1/2 teaspoon pie spice in a bowl; set aside.
Whisk together flour, brown sugar, baking powder, salt, and remaining 1/2 teaspoon pie spice in a bowl. Whisk together cider, egg, and vanilla in a separate bowl. Add wet ingredients to dry ingredients, mixing until just combined.
Peel and core apple. Coarsely grate half the apple and cut the other half into 1/4-inch pieces. Gently fold into batter.
Working in batches, drop spoonfuls of batter (about 2 tablespoons each) into oil. Fry, turning once, until golden brown, 2 to 4 minutes.
Toss warm fritters in sugar- spice mixture. Transfer to the cooling rack. Serve warm or at room temperature.