Cook the rice in 2 cups of chicken stock according to package directions until tender. Fluff with a fork and set aside.
Heat a large heavy-bottomed skillet over medium-high heat. Melt the butter with the olive oil.
Slice the smoked sausage into rounds and add to the skillet. Cook for 3–5 minutes until browned.
Add the chopped onion, red bell pepper, and celery. Cook for 2–3 minutes until the vegetables begin to soften.
Stir in the minced garlic and cook for 1 minute until fragrant.
Season the mixture with onion powder, garlic powder, smoked paprika, thyme, oregano, cayenne pepper, salt, and black pepper. Stir well to coat everything evenly.
Pour a splash of the remaining chicken stock into the skillet to deglaze the pan, scraping up the browned bits with a wooden spoon.
Add the cooked rice and stir until combined with the sausage and vegetables. Continue cooking for 2–3 minutes, adding more chicken stock if needed to keep the rice moist.
Remove from heat and transfer to a serving dish. Garnish with fresh parsley if desired and serve warm.