In a large skillet, cook bacon over medium heat until crisp. Remove bacon, and let drain on paper towels, reserving 1 tablespoon drippings in skillet.
Add onion to skillet; cook until softened, about 6 minutes. Add blackberries, brown sugar, vinegar, ¼ teaspoon salt, and ¼ teaspoon pepper. Using a potato masher, mash blackberries. Bring mixture to a boil; reduce heat, and simmer, stirring occasionally, until thickened, about 40 minutes. Spoon mixture into a bowl; let cool completely.
In a small bowl, stir together ricotta, Parmesan, chives, remaining ¼ teaspoon salt, and remaining ¼ teaspoon pepper. Spread about 2 teaspoons cheese mixture onto each baguette slice. Top with about 1 tablespoon blackberry mixture. Crumble bacon, and sprinkle over crostini. Sprinkle with additional pepper, to taste. Serve immediately.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/blackberry-sweet-onion-jam-crostini-recipe/