First, you will want to peel and de-vein your raw shrimp. When that is done, you will finely chop the shrimp. It is important to get it quite fine, or you may have issues with them staying together when you cook them.
Mix the finely chopped raw shrimp with the beaten egg, finely diced onion, bread crumbs, lemon juice, parsley flakes, Old Bay seasoning, and the garlic powder.
Preheat a nonstick skillet or griddle to medium heat, and melt the butter in the pan. We cook seafood with butter in our house, but you could use oil here if you prefer.
Divide the shrimp mixture into four equal amounts - for me, each burger was about 1/2 cup plus a tablespoon or so. Gently put the burgers into the preheated pan. It is very important not to flip them too soon, so be patient. These do have a tendency to fall apart if you aren't patient and gentle with them.
Depending on your stove and temperature, the first side will cook for 5-7 minutes prior to flipping. Flip gently, and cook the other side an additional 5-7 minutes. You will see the shrimp turning pink as they cook. A couple of minutes before the end of cooking time, sprinkle the burgers with the grated fresh Parmesan or Romano cheese.
When they are done, serve on a bun with tomato, avocado, and lettuce. I also had some Peruvian Green Sauce (recipe linked in the notes below) on mine, but a tartar sauce variety of your choice would also be good.
We made homemade air fryer french fries to go on the side of our shrimp burgers. I'll also link that recipe in the notes below.