Cook the pasta to just below package instructions, reserving 1 cup of the water when straining. The pasta will finish cooking in the sauce so you want them to be less than al dente.
Season both sides of the steak with the steak spice and set aside for at least the amount of time you cooked the steaks, then slice into strips
In a large pan heat vegetable oil on high heat until shimmering, add 1 tbsp butter and move around until fully melted
Add the steaks to the pan and fry 3 minutes per side, remove from the pan and set aside
Add the remaining butter and the onions to the pan and saute on medium-high for 1 minute, then add the garlic and saute for another minute
add the lemon juice and 1/2 cup pasta water, then scrape the pan for 30-60 seconds.
Reduce the heat to medium-low and add the milk, stirring to combine. Allow to simmer for 1 minute
stir in the parmesan, once absorbed add the tomatoes, spinach and other half cup of pasta water. Cover and cook on medium-low for 8-10 minutes.
Once the spinach has fully wilted, fold in the steak and pasta, cover and cook 1-2 minutes
Serve garnished with fresh parsley