In a saucepan, heat cream to simmering over high heat. Reduce heat to medium and whisk in chocolate until melted. Gently simmer sauce for 10 minutes. Set aside. Make a light sugar syrup by heating the water and sugar together in a medium size saute pan, stirring until the sugar is dissolved. Add the lemon juice and berries to syrup and cook over medium heat 2 to 3 minutes, shaking the pan gently to coat the berries with syrup. Add the butter and continue to cook, swirling the berries and butter around the pan, until butter is melted. Cook for another 5 minutes. Spoon berry compote into ramekins, drizzle with white chocolate sauce and serve.