Cook rice according to directions, until just al dente.
Pour 1 ½ Tbsp olive oil into a medium-sized stock pot or dutch oven. Add in onion, carrots, celery, parsnips, and mushrooms and stir. Cook for about 5 minutes, until softened. Add garlic and cook for another minute. Sprinkle in cayenne, salt, and pepper.
In a separate medium saucepan, cook chicken sausage in 1 Tbsp olive oil over medium heat until heated through and browned a bit.
Pour chicken stock into stockpot and bring to a boil. Reduce to a simmer and let cook another 5 minutes. Stir in chicken sausage.
In a separate small bowl, whisk together the flour and milk.
Add rice to stockpot and stir in flour/milk roux. Cook for 2 minutes.
Taste and add more salt, pepper, or cayenne if needed.