Coquilles St-Jacques is the kind of unapologetically rich shellfish dish that we used to be able to enjoy, before the book-writing dieticians and celebrity chefs ruined it for everybody.
8 oz button mushrooms, sliced
1 egg yolk
2 tsp minced tarragon
NOTE: You can make these ahead, and refrigerate until needed. Since they will be cold, you’ll need to bring back to temperature before you broil them. Preheat oven to 350 F. and bake for about 12-15 minutes (will depend on how you constructed them), or until the centers are just warm. Switch oven to broil, and broil on high as shown. Source recipe: https://foodwishes.blogspot.com/