Lay bacon out on a roasting pan in a single layer and bake for 10 minutes until just crispy - remember they will be going back into the oven with the oysters so you don't want to finish the bacon just yet. While the bacon is cooking, put the butter, garlic, shallots, bell pepper, celery, lemon juice, oregano, and cayenne pepper in a food processor; pulse until well combined, but still has texture. Season with salt and pepper, to taste.
Remove bacon from oven and cut each slice into 6 so you have a total 24 pieces. Lay oysters in their half shells out on a large roasting pan in a single layer. Place 1 tablespoon of the casino butter mixture on top of each oyster and place a piece of bacon on each. Bake oysters in the hot oven until bubbly, approximately 10 to 12 minutes. Finish with finely chopped, fresh flat-leaf parsley and serve.