They sound and look elegant, but they are quick and easy to make. Prepare 
as instructed or add a sprinkle of Parmesan cheese just before popping them into the oven. 

Ingredients
12 Mussels, cooked/shucked
1 tbsp (15ml) PC unsalted butter, melted
2 tbsp (25 ml) lemon juice
1/8 tsp (0.5 ml) salt
12 large mushroon caps 

Directions
Preheat oven to 450°F(230°C). Dip mussels in mixture of melted butter, 
lemon juice and salt. Place one mussel in each mushroom cap. Place in a 
lightly greased baking pan; pour remaining butter and lemon juice mixture 
over the mussels and mushroom caps. Bake in preheated oven for 10 
minutes. Serve hot.

Source: peishellfish.com