Allow butter, eggs, and sour cream to stand at room temperature 30 minutes. Meanwhile, grease and lightly flour 9x5x3-inch loaf pan; set aside. In bowl, stir together flour, baking powder, and baking soda; set aside.
Preheat oven to 325 F. In mixing bowl beat butter with electric mixer on medium to high speed 30 seconds. Gradually add sugar, beating 10 minutes or until very light and fluffy. Beat in vanilla. Add eggs 1 at a time, beating 1 minute after each addition, scraping bowl frequently. Alternately add flour mixture and sour cream to butter mixture, beating on low to medium speed after each addition just until combined. Pour batter into prepared pan.
Bake 60 to 75 minutes or until wooden pick inserted near center comes out clean. Cool on wire rack 10 minutes. Remove from pan; cool thoroughly on wire rack.
To assemble sandwiches, slice cake into 1/2-inch slices. Spread Lemon Butter on one side of eight cake slice. Top with peach and strawberry slices. Drizzle with caramel topping. Top with remaining cake slices. Makes 8 to 10 servings.
In medium bowl beat softened butter with electric mixer on medium to high speed 30 seconds. Add finely shredded lemon peel. Beat to combine. Gradually drizzle lemon juice; beat to combine. Use immediately or cover and chill butter up to 1 week. Let stand at room temperature 30 minutes before using.