Combine apples and juice; toss. Add 1/4 cup granulated sugar, cinnamon, and 1/4 teaspoon salt; toss to combine.
Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, the remaining 1/4 teaspoon salt, and baking powder in a bowl, stirring well. Place remaining 3/4 cup granulated sugar, 6 tablespoons butter, and cheese in a bowl; beat with a mixer at medium speed until light and fluffy. Add eggs, beating well. Stir in 1 teaspoon vanilla. Add flour mixture and buttermilk alternately to butter mixture, beginning and ending with flour mixture, beating just until combined. Stir in walnuts.
Scrape batter into a 13 x 9-inch metal baking pan coated with cooking spray. Arrange apples over batter. Melt remaining 2 tablespoons butter; brush over apples. Bake at 350° for 45 minutes or until set.
Combine preserves and juice; microwave at HIGH for 30 seconds or until melted, stirring once. Brush apricot mixture over apples; cool. Cut into 15 squares.