As part of our “use it up” series, today’s lunch is the remainder of last night’s fish pie. 
It started with leftover celeriac gratin, to which we added some steamed carrots and sliced mushrooms. Any leftover veg would do, though. We also had part of a container of whipping cream, and of course, the last of our amazing roast haddock from Hooked. Again, if you have other leftover fish, or even a tin of wild-caught salmon, this will work nicely. No whipping cream? Try regular milk with a tablespoon of cornstarch stirred in.
Heat all of this to bubbling over gentle heat in an ovenproof dish, while you heat your oven to 400F
Meanwhile, make the biscuit topping like so:
In a medium bowl, combine 1 c each white flour and whole wheat flour. This makes a thick topping for four, otherwise feel free to halve it! Stir in 1/2 T brown sugar, 2 t baking powder and 1/2 t baking soda. Give a grind of salt and pepper. Quickly stir in 1 c fat free yogurt, just until blended. You may need to knead a couple of times by hand. Turn out onto a floured surface and pat to the size of your casserole. Place on top of the fish filling.
After 15 minutes drop the heat to 350 and bake another 15 minutes. At this point you can turn the heat off and it will stay warm in the oven for another 15-20 if someone is running late.
Leftovers? Reheat from refrigerator cold by placing in a cold oven. Turn heat to 350. When your oven comes up to 350, time for 15 minutes and you’re set.
Also, the same topping can be rolled into biscuits – skip the pepper and follow the method as given. Roll 1″ thick and cut into circles. Bake on a cookie sheet w parchment at 400 for 20 minutes.)