Pat the sirloin steak cubes dry with paper towels to remove excess moisture.
In a large skillet, heat the olive oil over medium-high heat.
Add the steak cubes in batches and sear each side for about 1-2 minutes until browned but not cooked through. Transfer seared steak bites to the crockpot.
In the same skillet, reduce heat to medium and add 2 tablespoons of butter.
Add the minced garlic and cook for 1 minute until fragrant, stirring constantly to prevent burning.
Add Worcestershire sauce, beef broth, salt, black pepper, dried parsley, smoked paprika, and crushed red pepper flakes to the skillet. Stir to combine and bring to a simmer.
Pour the garlic butter sauce over the steak bites in the crockpot.
Add the remaining 2 tablespoons of butter on top of the steak bites.
Cover the crockpot and cook on low for 2 to 2.5 hours until the steak bites are tender and infused with the garlic butter sauce.
Once cooked, stir gently to coat the steak bites evenly with the sauce before serving.