Bring a large pot of water to a rolling boil. Add 1 tablespoon kosher salt, then cook the pasta according to package directions until al dente. Before draining, reserve 1 cup of the hot pasta cooking water, then drain the pasta and set aside.
While the pasta cooks, combine the cottage cheese, milk and 1/2 cup of the grated Parmesan in a blender or food processor. Blend until very smooth and creamy, about 30–45 seconds. Scrape down the sides and blend again if needed. This creates the high-protein Alfredo base.
Heat the olive oil and butter in a large skillet over medium heat until the butter melts. Add the minced garlic and cook, stirring, for about 30 seconds until fragrant but not browned.
Pour the blended cottage cheese mixture into the skillet with the garlic. Stir constantly and warm gently — do not boil — until the sauce loosens, about 1–2 minutes.
Add the remaining 1/4 cup grated Parmesan, black pepper, lemon zest and 1/4 teaspoon salt to the sauce. If the sauce seems too thick, whisk in 2–4 tablespoons of the reserved pasta water at a time until you reach a silky consistency.
Add the drained pasta directly to the skillet and toss with tongs so the hot pasta is fully coated. If needed, add more reserved pasta water to help the sauce cling to the noodles. Continue tossing over low heat for 1 minute to marry the flavors.
Turn off the heat and let the pasta rest in the pan for 1–2 minutes; the sauce will thicken slightly as it cools. Taste and adjust seasoning with extra salt or pepper if desired.
Serve immediately, garnished with the remaining Parmesan (if you like) and chopped parsley. A light squeeze of lemon over individual servings brightens the dish even more.