In a pan over high heat, bring salted water to a boil. Meanwhile, prepare your asparagus for blanching. Gently bend each asparagus spear until it breaks naturally (or, bend one spear, take note of where it breaks naturally, and slice the remainder with a knife in the same spot). Discard the woody ends, then slice each spear into 1 to 2 inch pieces.
Once water is boiling, add asparagus and blanch for 2-3 minutes (depending on thickness). Test with a fork for your desired firmness. Remove from heat immediately and drain.
In a large bowl, add unsalted butter, lemon zest, salt, and pepper. Add hot asparagus and allow butter to melt. Toss to coat.
Sprinkle with Parmesan cheese and serve immediately.
Any cooked vegetables can be substituted for asparagus - skip to step three and toss vegetable of your choice in lemon butter mixture.
Freshly grated parmesan cheese is best for this recipe. Store bought parmesan cheeses (in a canister) often contain anti-clumping powders, which causes a grainy texture when cheese melts.
Cooked asparagus will keep for three days or more in a sealed container in the refrigerator.