Heat 1 tbsp butter in a large skillet over medium-high heat until melted and shimmering, about 2 minutes.

Pat the sirloin steak dry, season generously with salt and pepper, then sear for 3 minutes per side until a deep golden crust forms.

Transfer the steak to a cutting board and let it rest 5 minutes, then slice against the grain into thin, juicy strips.

Sauté garlic cloves in the same pan over medium heat for 30 seconds until fragrant, scraping up the flavorful brown bits.

Pour in 1 cup beef broth and scrape the pan bottom, simmering for 2 minutes until slightly reduced and savory aromas rise.

Stir in 1 tbsp Dijon mustard and 1 tsp Worcestershire sauce, blending until smooth, then pour in 1 cup heavy cream.

Lower heat to medium-low and gently simmer the sauce for 3 minutes until thickened and velvety.

Bring a large pot of salted water to a rolling boil, add 12 oz egg noodles, and cook 7 minutes until al dente.

Drain noodles, reserving ¼ cup cooking water to loosen the sauce if needed.

Add sliced steak and cooked noodles into the sauce, tossing gently off heat until every strand glistens and is fully coated.

Sprinkle with fresh parsley and red pepper flakes if desired for a bright, colorful finish.