Cut a pocket into the side of each salmon fillet. Place each fillet on a flat surface and slice into the side with a sharp knife. Be careful not to cut all of the way through the fish. When you insert the knife into the side, do so at an angle so that the pocket inside of the fish is wider than the opening where you inserted the knife. Make sense? The idea is to make a space for the stuffing to go into, but not run out of the fillet. Rub fillets with olive oil and then season with salt and pepper. Melt butter over medium-high heat in a large skillet. Add garlic and onion and sauté until onions are translucent. Add shrimp, salt, cayenne pepper, black pepper, white pepper, oregano flakes and Tabasco. Sauté until shrimp is barely pink. Transfer to bowl and allow to cool. When cooled, add parsley, bread crumbs and cream cheese to shrimp mixture and gently stir to blend ingredients. Place about 1/4 cup of the stuffing mixture inside the pocket of each salmon fillet. Spread the stuffing out evenly inside the pocket.
Place the stuffed fillets on a shallow baking dish or pan. Place in a preheated 375 degree oven for 15 minutes or until salmon is just cooked. Top each with sliced avocado before serving.