Wash asparagus spears. Trim woody ends and peel the lower quarter of the thicker asparagus spears with a vegetable peeler to remove the fibrous skin. Chop diagonal into about 1/3-inch thick slices. Leave the tips whole.

Cook the pasta in salted water according to the packaging instructions.

Melt butter in a large pan over medium heat and sauté the chopped asparagus including tips for about 5 minutes. Add a bit of lemon zest and stir.

Drain pasta and set some of the cooking water aside. Let pasta sit in the colander while making the sauce.

Add crème fraîche, some lemon zest, and black pepper to the empty pasta pot. Heat until crème fraîche becomes liquid while stirring.

Add 1 tablespoon pasta cooking water at a time while stirring to get a nice luscious and creamy sauce.

Add grated parmesan and more pasta water if needed. The sauce should resemble heavy cream.

Squeeze some lemon juice over the asparagus in the pan, then stir. Add the drained pasta and most of the asparagus pieces to the pot with the sauce and stir to combine.

Serve the pasta with the remaining asparagus, some lemon zest, parmesan, and black pepper.