Heat milk and cream in saucepan over medium heat until simmering, about 5 minutes. Slowly whisk in Parmesan and Romano cheeses. Remove from heat.

Whisk egg yolks together in a heat-proof bowl; slowly whisk in about 1/4 cup hot cream mixture to temper eggs. Slowly whisk egg yolk mixture into saucepan. Season with salt and pepper. Allow Alfredo sauce to cool; refrigerate until needed.

Whisk salad dressing, rosemary, and lemon juice together in a large bowl. Add steak and toss to coat. Cover bowl with plastic wrap and marinate in refrigerator for 4 hours.

Preheat an outdoor grill for medium heat and lightly oil the grate.

Fill a large pot with salted water and bring to a rolling boil. Cook fettuccine until tender, about 8 minutes.

Heat 2 cups Alfredo sauce in saucepan over medium heat. Add spinach and 2 tablespoons Gorgonzola cheese.

Remove steak from marinade and shake off excess. Discard remaining marinade. Cook on grill to desired doneness, 5 to 10 minutes.

Pour hot Alfredo sauce into a large serving bowl. Add cooked pasta; toss to combine. Sprinkle remaining Gorgonzola cheese on top. Add grilled steak; drizzle with balsamic glaze. Garnish with parsley.