Wash the asparagus, trim the ends, peel lower quarter, and slice into 1/3-inch pieces, reserving tips.

Boil salted water in a large pot. Cook spaghetti for 9-11 minutes until al dente, reserving 1 cup of pasta water.

Melt salted butter in a skillet, add asparagus and sauté for 5 minutes until crisp-tender. Add zest of half a lemon.

In the empty pasta pot, mix creme fraiche, remaining lemon zest, and black pepper. Heat until warm and velvety.

Gradually add reserved pasta water to sauce until creamy and pourable.

Stir in grated Parmesan until melted and integrated into sauce. Adjust consistency as needed with pasta water.

Squeeze juice of half a lemon over asparagus, then toss spaghetti with asparagus and sauce until well combined.

Serve with reserved asparagus tips, lemon zest, and a sprinkle of grated Parmesan and black pepper.