Duck Breasts with Cardamon Sauce

Loris and I were served this during our stay with German friends, Ulla and Ule, this spring.  It was incredible, by far the best duck recipe I have eaten.  
Last week we tried the recipe at home and it was sensational.  

Polderside duck breasts are fabulous.   You can get them at Famous Foods.   We used frozen duck breasts from Stongs.

The flavourings are a little touchy.   Add slowly and taste as you go.   Hold back on the Grand Marnier and salt but be generous with the cardamon.   You can probably skip the balsamic vinegar.

Ingredients:
2 duck breasts
Olive oil
6 tsp. Ground cardamon
4 Tbsp. Grand Marnier
1 Tbsp. grapeseed oil (highest burn point)
1 cup cream
2 Tbsp. mascarpone
2 tsp. balsamic vinegar
Scant tsp. sea salt
Freshly ground pepper

Instructions:
Marinade:
The day before, or at least 2 hours before, score the fat side of the duck breasts in a diamond shape using a sharp knife.
Marinate in a ziploc bag with olive oil, 3 tsp. ground cardamon, and 2 Tbsp. Grand Marnier.
Breasts:
Heat a frying pan on medium, and then add the grapeseed oil.  
Sear the fat side of each breast for 8 minutes, then turn and sear the meat side for 6 minutes.  Don't move the breast in the pan.  Turn the heat down a touch if the breasts start to burn.
Wrap tightly n aluminum foil to keep the juices in.  Wrap the package with a towel to keep warm and rest 15 minutes while you make the sauce.
Sauce:
Pour the fat out of the frying pan.
Heat the pan.
Add the cream and stirt to deglaze the pan.
Strain the sauce through a seive and return to the pan (I didn't bother).
Add mascarpone, 2 Tbsp. Grand Marnier, balsamic vinegar, and 3 tsp. ground cardamon. 
Stir and turn down the heat to simmer for a few minutes.
Taste and adjust the seasonings.
Season with salt and pepper to taste.
Slice the duck breasts and serve on a platter.
Serve the sauce on the side in a gravy boat.