1. Cake: Preheat oven to 350 degrees. Coat an 8 1/2-by-4 1/2-inch loaf pan with cooking spray. Line with parchment, leaving a 2-inch overhang on long sides. Coat parchment with cooking spray, then dust with flour, tapping out excess. Whisk together flour, salt, and baking powder in a bowl.

2. Beat butter and cream cheese in a large bowl until creamy. Add granulated sugar and beat until light and fluffy, about 3 minutes. Add eggs, one at a time, beating to combine after each addition. Beat in vanilla. With mixer on low speed, gradually add flour mixture, beating to combine.

3. Transfer batter to prepared pan, smoothing top with an offset spatula. Bake on a baking sheet until a tester inserted in center comes out clean, about 1 hour, 10 minutes, tenting with foil after 50 minutes. Let cool 10 minutes in pan on a wire rack, then turn out onto rack, top-side up, and let cool completely, about 3 hours.

4. Slice cake in half horizontally. Slice each portion in half again to create 4 equal slices.

5. Filling: Bring 2 cups peaches, granulated sugar, salt, and 1/3 cup water to a boil in a medium saucepan. Reduce to a simmer and cook, covered, until fruit is tender, about 5 minutes. Let cool slightly, then puree mixture in a food processor until smooth (you should have about 1 1/2 cups).

6. Prepare an ice-water bath. Sprinkle gelatin over 1/4 cup water in a small saucepan. Let sit until softened, about 5 minutes. Heat over medium, stirring until gelatin is dissolved. Stir in peach mixture to combine. Transfer to a large bowl; place in ice bath and let stand, stirring frequently, until beginning to set, about 6 minutes. Stir in remaining 1 1/2 cups peaches and cherries. Whisk cream to stiff peaks, then fold into peach mixture. Continue stirring over ice bath until mixture will hold its shape when dropped off a spoon.

7. Line loaf pan with plastic wrap, leaving an overhang on all sides. Place bottom cake layer in pan. Spread 1 cup peach mixture over cake. Repeat with remaining cake layers and filling, ending with top cake layer. Wrap plastic around cake and refrigerate until set, at least 4 hours and up to 2 days, before removing from pan using plastic. (If desired, trim edges of assembled cake.) Dust with confectioners' sugar just before serving.