Preheat air fryer to 350°. Grease and flour a 6-in. round baking pan. In a large bowl, whisk egg, buttermilk, 1/3 cup sugar, oil, brown sugar, orange zest and vanilla. In another bowl, whisk flours, baking powder, 1 teaspoon pumpkin pie spice, baking soda and salt. Gradually beat into egg mixture. Fold in carrots and dried cranberries. Pour into prepared pan.
In a small bowl, combine walnuts, remaining 2 tablespoons sugar and remaining 1 teaspoon pumpkin spice. Sprinkle evenly over batter. Gently place pan in the basket of a large air fryer.
Cook until a toothpick inserted in center comes out clean, 35-40 minutes. Cover tightly with foil if top gets too dark. Cool in pan on a wire rack for 10 minutes before removing from pan. Serve warm.