1. Fire up your Ooni pizza oven.
2. Soak the mussels in a bowl of salted water for 10–15 minutes.
3. Place the Sizzler Pan inside your Ooni to warm up.
4. Add the butter, shallots and garlic to a bowl.
5. Remove the Sizzler from the oven and add the mussels to the dish along with the butter mixture and place inside the Ooni.
6. Steam the mussels for 4 minutes, or until they have opened.
7. Remove the sizzler from the oven and split the mussels into four bowls, topping them with their delicious sauce, lemon, and a sprinkle of parsley.