Step 1

Bake the Roux. Preheat oven to 425 degrees. Line a large rimmed baking sheet with foil. Spread the flour out on the pan. Bake, raking the edges in and pushing the center to the outsides every 10 minutes. Keep doing this until it gets the color of ground cinnamon. This will take about 1 hour 10 minutes to 1 1/2 hours. Cool completely and store in an airtight container in a cool, dark place for up to 3 months.

Step 2

Make the Holy Trinity. Spread onion, celery, and bell peppers out on 2 baking sheets lined with parchment paper. Freeze for 2 hours. Transfer to freezer bags. Store in freezer until needed. Thaw required amount for 2 hours in a strainer before using.

Step 3

Melt 1 tablespoon butter over medium-high heat in a large Dutch oven. Add andouille and cook, stirring often until browned, about 4 minutes. Remove sausage with a slotted spoon and set aside.

Step 4

Add remaining butter and cook Holy Trinity until softened, about 5 minutes.

Step 5

Add garlic, Cajun seasoning, thyme, and bay leaf and cook 1 minute.

Step 6

Stir in 2 cups of chicken broth and use a wooden spoon to scrape any brown bits off the bottom.

Step 7

In a large bowl, whisk together dry roux and remaining 2 cups of chicken broth until completely smooth. Add to Dutch oven and bring to a boil. Reduce heat and simmer 20 minutes. Add chicken for the last 5 minutes.

Step 8

Season to taste with salt and pepper and stir in file powder. Serve with rice and green onions.