Cook fettuccine in salted boiling water until al dente. Drain and set aside, reserving some pasta water.
Heat olive oil in a skillet over medium-high heat. Season steak pieces with salt and pepper, then sear until browned. Remove from skillet.
In the same skillet, melt butter and sauté garlic until fragrant. Add heavy cream and simmer until thickened.
Stir in Parmesan cheese until melted. Add Gorgonzola and continue stirring until smooth.
Toss in cooked pasta, adding reserved pasta water as needed to adjust the sauce consistency.
Add spinach and let it wilt. Return steak to the skillet and toss everything to combine.