In a medium bowl, toss chicken breasts with olive oil, salt, pepper, garlic powder, and oregano.
Preheat a grill or grill pan to medium-high heat.
Grill chicken for 6 to 8 minutes per side, or until the internal temperature reaches 165°F (74°C). Set aside to rest for 5 minutes.
Steam or blanch broccoli florets for 3 to 4 minutes until tender-crisp and bright green.
In a small saucepan over medium heat, melt the butter and sauté the minced garlic for 1 minute until fragrant.
Pour in the heavy cream and simmer for 5 minutes until slightly reduced.
Whisk in the parmesan cheese until the sauce is smooth and thickened. Season with salt and pepper as needed.
Slice the grilled chicken into thin strips.
Divide the cooked rice or quinoa into four bowls. Top with chicken and broccoli. Drizzle the creamy garlic sauce over each bowl.