Bring a large pot of salted water to a boil. Add linguine and cook according to package instructions until al dente. Drain and set aside.
Pat the steak cubes dry with paper towels. Season evenly with kosher salt and black pepper.
In a large skillet, heat olive oil over medium-high heat until shimmering.
Add the steak bites in a single layer, cooking in batches if necessary to avoid overcrowding. Sear for 2 to 3 minutes without moving to develop a crust, then flip and cook an additional 2 minutes until browned and cooked to desired doneness. Remove steak bites from skillet and set aside on a plate.
Reduce heat to medium and add 2 tablespoons of butter to the skillet. Once melted, add the minced garlic and crushed red pepper flakes. Sauté for 1 minute until fragrant, stirring constantly to prevent burning.
Add the cooked linguine to the skillet and toss to coat in the garlic butter sauce.
Return the steak bites to the skillet and gently toss with the linguine and sauce to combine and warm through, about 1 to 2 minutes.
Remove from heat. Stir in the remaining 1 tablespoon of butter and chopped fresh parsley until the butter is melted and the parsley is evenly distributed.
Divide the garlic butter steak bites with linguine among serving plates. Sprinkle each serving with grated Parmesan cheese before serving.