Slice mushrooms and clean scallops, cut in half.
Cook 3 minutes with 2 Tbsps butter, add lemon juice.
Cook 1 minute and set aside.
Blend 1 Tbsp butter, 1 tsp flour and 1/2 cup cream in saucepan over low heat.
Stir constantly over low to medium heat and bring to boiling point.
Add 2 egg yolks, slightly beaten, and 2 Tbsps sherry; add the scallops and mushrooms.
Reduce heat and stir well.
If mixture curdles from overcooking, add a little milk and stir till smooth again.
Season to taste with salt and cayenne.