01 - Bring a large pot of salted water to a rolling boil. Add pasta and cook until al dente according to package directions. Drain thoroughly, reserving 1/2 cup of the starchy cooking water for later sauce adjustment.
02 - Heat olive oil in a large skillet over medium-high heat until shimmering. Add the sliced beef strips in a single layer, seasoning generously with salt, pepper, and smoked paprika. Cook for 2-3 minutes, developing a browned crust on one side before flipping. Transfer the seared beef to a plate, leaving any rendered fat in the skillet.
03 - In the same skillet over medium heat, add the chopped onion. Sauté for 3-4 minutes until translucent and lightly golden. Add the minced garlic and cook for 30 seconds until fragrant, being careful not to burn it.
04 - Reduce heat to medium. Add cottage cheese, Greek yogurt, and beef broth to the skillet. Stir continuously with a whisk or wooden spoon until the mixture becomes smooth and creamy. If using protein powder, whisk it in gradually to prevent clumping until fully dissolved.
05 - Add baby spinach leaves to the creamy sauce. Cook for 1-2 minutes, stirring gently until the spinach is just wilted but still vibrant green.
06 - Return the cooked beef and any accumulated juices to the skillet. Add the drained pasta and toss everything together until well coated with the sauce. If the sauce appears too thick, gradually add the reserved pasta water, 1 tablespoon at a time, until you achieve the desired creamy consistency.
07 - Sprinkle with Italian herbs and adjust seasoning with additional salt and pepper as needed. Serve immediately while hot, garnished with grated Parmesan and fresh parsley if desired.