01 - Preheat oven to 400°F. Slice tops off garlic bulbs to expose cloves, drizzle with 1 tbsp olive oil, wrap in foil, and roast for 30 minutes until soft and golden.
02 - Pat flank steak dry and rub with 1 tbsp olive oil, salt, and pepper.
03 - Heat a large ovenproof skillet over medium-high heat. Sear steak for 3–4 minutes per side until well browned.
04 - Transfer skillet to oven and roast for 6–8 minutes for medium-rare, or adjust for desired doneness.
05 - Remove steak from oven, transfer to a plate, and tent loosely with foil. Let rest for 10 minutes.
06 - Squeeze roasted garlic cloves from bulbs into a small saucepan. Add broth and bring to a simmer over medium heat, whisking to break up garlic.
07 - Add cream, butter, Dijon mustard, and lemon juice. Simmer gently for 2–3 minutes, whisking until smooth and slightly thickened. Season with salt and pepper to taste.
08 - Slice flank steak thinly across the grain. Spoon roasted garlic sauce over steak. Garnish with fresh parsley if desired.