Preparation Bring blackberries, lemon juice, and sugar to a boil in a medium saucepan. Reduce heat and simmer, stirring occasionally, until berries soften and juices thicken slightly, 10–15 minutes. Remove from heat; stir in maple syrup. Let cool slightly before serving. DO AHEAD: Syrup can be made 1 day ahead. Let cool; cover and chill.
Preparation Bring blackberries, lemon juice, and sugar to a boil in a medium saucepan. Reduce heat and simmer, stirring occasionally, until berries soften and juices thicken slightly, 10–15 minutes. Remove from heat; stir in maple syrup. Let cool slightly before serving. DO AHEAD: Syrup can be made 1 day ahead. Let cool; cover and chill.