This idea came to me in a flash of inspiration. It's cooking even as I type, and WOW does it smell good!

I entered the whole thing into Master Cook for a nutritional analysis, which I'll include at the end.

Ingredients:
1 pound cooked, cut-up chicken (I used breast meat)
1 pound (1 bag) frozen broccoli cuts
1 cup shredded Cheddar cheese
1 cup EACH sour cream and heavy cream
1 cup walnuts (pieces, chopped, your choice)
1 tsp salt
1/2 tsp pepper
1 tsp tarragon leaves

Lightly butter an 11x7 casserole dish. Layer the broccoli, chicken, and cheese, making sure the latter two are evenly distributed. Combine the creams and seasonings, and pour over the layers, again taking care to pour evenly. Sprinkle the walnuts over everything, again (you guessed it) being sure to distribute them evenly.

Cover with foil (or the casserole lid if it has one) and bake for 45 minutes in a 350-degree oven. Then remove the cover and bake for another 15-25 minutes, or until most of the liquid is gone.

Serves 6.

Analysis:
Calories: 433/serving
Fat (grams): 38
Carbs (grams): 7 [fiber: 2g]
Protein (grams): 18

Percentage of calories from fat: 77.2
Percentage of calories from carbs: 6.2
Percentage of calories from protein: 16.6