Remove steaks from refrigerator 30 minutes before cooking to reach room temperature; pat dry thoroughly with paper towels to ensure a proper sear.

Season all sides of the steaks generously with kosher salt and cracked black pepper.

Heat a heavy cast-iron skillet over high heat until smoking; add grapeseed oil and swirl to coat the surface.

Carefully place steaks in the skillet and sear for 3 to 4 minutes per side until a dark golden-brown crust forms.

Reduce heat to medium; add the butter, smashed garlic cloves, and thyme sprigs to the skillet.

Tilt the pan and use a large spoon to continuously baste the steaks with the foaming garlic butter for 2 to 3 minutes until internal temperature reaches 130°F (54°C) for medium-rare.

Transfer steaks to a warm plate and rest for 10 minutes to allow juices to redistribute.

In a separate small saucepan, bring the heavy cream to a gentle simmer over medium heat.

Whisk in the grated Parmesan cheese and garlic powder, stirring constantly until the cheese is melted and the sauce has thickened.

Slice the rested steaks against the grain, drape with the Parmesan cream sauce, and garnish with fresh parsley.