Preheat the grill to 450–500°F. Brush the steak with olive oil and season evenly with salt, black pepper, smoked paprika, and garlic powder.
Grill the steak for 3–5 minutes per side, depending on thickness and desired doneness. Remove from the grill and let rest for 5–10 minutes, then slice thinly against the grain.
Prepare the fries according to package directions until crispy and golden.
Air fryer: 400°F for 12–15 minutes
Oven: 425°F for 20–25 minutes
Deep fryer: 350°F until crisp
While the fries cook, melt the butter in a saucepan over medium heat. Add the minced garlic and sauté for 1–2 minutes until fragrant.
Pour in the heavy cream and bring to a gentle simmer. Stir in the Parmesan cheese and whisk until melted and slightly thickened, about 3–4 minutes.
Season the sauce with black pepper and salt to taste. Stir in mayonnaise if using.
Arrange the hot fries on a serving platter or skillet. Top with sliced grilled steak and generously drizzle with the garlic Parmesan sauce.
Garnish with fresh parsley and serve immediately.