Melt the sugar with the Calvados on a low heat until sugar is dissolved and the mixture starts to thicken slightly.
Allow to cool.
Soak the duck breasts in the Calvados glaze on all sides, then transfer to a baking tray and bake for 15 minutes at 180C/350/Gas 4.
For the cabbage, melt the butter on a low heat, then fry off the garlic, onion, and bacon. When the onions have softened, add the cabbage and sweat on a low heat for about 30 minutes.
Allow the duck to rest for a few minutes before serving alongside the cabbage.