1. Bring a large pot of salted water to a boil. Add the linguine and cook according to package instructions until al dente, usually about 9-11 minutes. Reserve 1 cup of pasta water before draining.
2. While the pasta cooks, season the cubed steak generously with half the salt and pepper.
3. Heat olive oil and 2 tablespoons of butter in a large skillet over medium-high heat. Once hot, add the steak bites in a single layer. Let them sear without moving for about 2 minutes to get a nice crust, then stir and cook for another 2-3 minutes until cooked to your liking (medium-rare to medium works best). Remove the steak bites to a plate and tent with foil to keep warm.
4. Reduce the heat to medium, add the remaining 2 tablespoons of butter to the skillet, and stir in the minced garlic. Cook for about 1 minute until fragrant but not browned.
5. Add the fresh spinach to the skillet. Toss with the garlic butter until wilted, about 2-3 minutes. If using, sprinkle in the red pepper flakes here.
6. Return the steak bites to the skillet, then add the drained linguine. Toss everything together, adding reserved pasta water a little at a time until the sauce coats the pasta nicely and everything is warm.
7. Remove from heat, squeeze lemon juice over the top if using, and stir in the grated Parmesan cheese. Taste and adjust seasoning with remaining salt and pepper as needed.
8. Serve immediately, garnished with extra Parmesan if you like.

One thing I’ve learned from cooking with kids underfoot is to keep the steps simple and the pans minimal. This recipe only needs one skillet, which means less cleanup and more time to sit down and enjoy the meal with your family. Plus, that searing step really locks in flavor, so don’t rush it!