Cook the Pasta: Boil the linguine in salted water according to package instructions, until just shy of al dente. Reserve ½ cup of pasta water, then drain the pasta and set aside.

Prepare the Feta Sauce: In a bowl, whisk together the lemon zest, lemon juice, and olive oil until well combined. Add the crumbled feta and a pinch of black pepper, whisking until the sauce is creamy and mostly uniform in texture. Set aside.

Cook the Asparagus: In a large skillet over medium heat, heat 1 tablespoon of olive oil. Add the minced garlic and sauté until fragrant, about 1 minute. Add the asparagus pieces, season with salt and pepper, and cook until tender-crisp, about 5-7 minutes. Remove the asparagus from the skillet and set aside.

Make the Hot Pasta Sauce: In the same skillet, melt the butter over medium heat. Add the heavy cream and bring to a gentle simmer. In a small cup, whisk together the flour and water until smooth, then stir this mixture into the simmering cream. Continue to cook, stirring frequently, until the sauce thickens, about 10 minutes. Stir in the chopped parsley, salt, and pepper.

Combine and Serve: Add the cooked pasta to the hot pasta sauce, tossing to coat evenly. Remove from heat and pour over the lemon feta sauce, mixing well. Gently fold in the cooked asparagus.

Enjoy: Serve immediately, garnished with additional parsley if desired.