01 - Preheat your oven to 400°F. Rub the potatoes with olive oil and sea salt, prick each potato with a fork several times, and place directly on the oven rack. Bake for 50–60 minutes, or until potatoes are tender when pierced with a knife.
02 - While potatoes are baking, heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add steak cubes and sear until browned on all sides, about 3–4 minutes. Remove steak from pan and set aside.
03 - In the same skillet, add diced onion and bell pepper. Sauté for 3–4 minutes until softened. Add minced garlic, thyme, black pepper, and salt; cook for 1 minute until fragrant. Return steak to the pan, toss to combine, and remove from heat.
04 - For the Parmesan cream sauce, melt butter in a small saucepan over medium heat. Whisk in flour and cook for 1 minute. Gradually add milk and heavy cream, whisking constantly until smooth and thickened, about 3–4 minutes.
05 - Reduce heat to low. Stir in grated Parmesan, nutmeg, salt, and white pepper until cheese is melted and sauce is smooth. Remove from heat and keep warm.
06 - Once potatoes are baked, let them cool slightly. Slice each potato lengthwise and gently scoop out some of the flesh, creating a cavity (reserve scooped potato for another use).
07 - Fill each potato with the steak and vegetable mixture. Drizzle generously with Parmesan cream sauce.
08 - Garnish with chopped chives and extra Parmesan, if desired. Serve immediately.