Low Carb Fish Pie

2 lbs. flounder or other thin fish
grated rind of one lemon
juice of 1/2 lemon
1 large shallot, diced small
1 tblsp olive oil
8 oz. creme fraiche or sour cream
2 egg yolks
1 tblsp chopped fresh parsley
salt and pepper to taste
2 tblsp grated parmesan
1 medium spaghetti squash
2-4 tblsp grated cheddar

Preheat oven to 400.  Grease a pan, maybe 9x12, and lay out the raw fish in an even layer.  Sprinkle fish with half the lemon peel and all the lemon juice.  Cook the shallots in olive oil until they begin to brown.  Remove from heat and add creme fraiche and then egg yolks (and 1-2  tblsp potato starch if you want a thicker sauce).  Stir in parsley, the other half the lemon peel, salt and pepper, and parmesan.  Shred cooked spaghetti squash into a bowl and mix with the sauce.  Layer squash mixture over the fish.  Sprinkle with grated cheddar.  Cook at 400 for 30-40 minutes, or until it begins to bubble.