Pat the beef chunks dry with paper towels and season generously with salt and black pepper.

(Optional) Heat a splash of oil in a skillet over medium-high heat. Sear the beef chunks for 2–3 minutes per side until browned — this boosts flavor but can be skipped if you’re short on time.

Place the halved baby potatoes into the bottom of the slow cooker, then nestle the seared or raw beef pieces on top. Add sliced onion if using.

In a small bowl, combine the melted butter with minced garlic, Italian herbs, and crushed red pepper flakes (if using).

Pour the beef broth over the meat and potatoes, then drizzle the garlic butter mixture evenly over everything.

Cover and cook on LOW for 7–8 hours or HIGH for 4–5 hours, until the beef is fork-tender and the potatoes are soft but not falling apart.

Taste and adjust seasoning with salt and pepper. If the sauce is too thin, leave the lid off for 10–15 minutes to reduce slightly.

Serve warm, garnished with chopped fresh parsley if desired.