Melt the butter on low heat. Scrub the lemon clean and grate off the lemon zest. Squeeze the lemon.
Mix the melted butter with with the crumbs and divide over the 4 bowls or glasses.
Stir the cream cheese with the lemon zest, juice and sugar. Beat the whipping cream and mix in with the cream cheese. Divide over the bowls/glasses and put in the fridge for 1 hour.
Save a handful of blueberries. Take the rest of the blueberries, water and cornstarch and bring to a boil. Let it simmer for 4 minutes on low heat. While simmering crush the berries a little bit. Let it cool.
Divide the sauce over the bowls/glasses and decorate with the blueberries.