A food processor with a dicing attachment helped me with this.
Grease a small baking dish with melted butter. Cut the onion into rings, and put the avocado on top. Add a little salt. Season with your favorite seasonings.
Defrost the shrimp, peel off the shell and lay them on top of the avocado. Sprinkle with soy sauce.
Sprinkle with lemon juice.
Cut the mozzarella into cubes and put it in the gaps between the shrimp. Pour in the cream.
The final layer is finely grated parmesan.
Bake in the oven for 7-10 minutes. I have an electric one. I baked on the middle shelf in convection mode at 170C for 10 minutes. Do not close the lid from the top.