My favourite (almost the only) way I eat fish is with this sauce, though I never measured anything until now. You can play with the ingredient amounts and it should still come out nicely. DH loves it, too. Pictured below with a side of mashed cauliflower and chicken gravy.

This is for two servings.

2 Tbsp butter
1/4 c heavy cream
1/2 tsp dried dill
1/4 tsp garlic powder

Combine ingredients and simmer gently until desired thickness. Stir often.

I do it while the fish is baking, on the 'simmer' burner. At the end, I'll pour any juices from the cooked fish into the sauce as well. I usually season the fish with just salt and pepper or a bit of Montreal steak spice.

Per serving, minus any cooking juices:

22 g fat
1 g carb
1 g protein
206 calories