Melt the butter in a large Dutch oven over medium heat. Make a roux by adding the flour and stirring continuously.
Over medium heat, stir the roux for 5 to 7 minutes until it turns peanut butter-coloured.
To the roux, add the onions, bell peppers, celery, and garlic, and cook for 10 minutes, stirring often.
Season the tomatoes with the bay leaves, salt, cayenne, and 1 tablespoon of Essence.
After cooking the tomatoes for 2 to 3 minutes, whisk in the shrimp stock.
Boil the pot, then reduce the heat to a simmer. For 45 minutes, cook the etouffée, stirring occasionally.
Mix the remaining tablespoon of Essence with the shrimp and add them to the pot. Stir well to ensure that all shrimp are evenly coated.
Depending on the size of the shrimp, cook them for 5 to 7 minutes. In the same pot, add the chopped parsley and stir to combine.
With steamed white rice, serve the etouffée. green onion Garnish with the tops.