Preheat oven to 350°. Beat first 2 ingredients and 1 cup granulated sugar at medium speed with an electric mixer until creamy. Add eggs, 1 at a time, beating just until blended after each addition. Stir in vanilla.
Stir together baking powder, salt, and 3 cups flour; gradually add to butter mixture, beating just until blended. Spread three-fourths of batter in a greased and floured 13- x 9-inch pan; sprinkle with blackberries.
Stir together remaining 1/2 cup granulated sugar and 1/4 cup flour in a medium bowl; add peaches and bourbon, stirring to coat. Spoon mixture over blackberries.
Stir pecans into remaining batter; dollop over peach mixture.
Bake at 350° for 1 hour or until golden and bubbly. Cool completely on a wire rack (about 1 hour). Cut into bars.
Note: We tested with Diamond of California Glazed Pecans.