Spiralize the zucchini into noodles. If the zucchini seems especially wet, spread the noodles over a clean kitchen towel and gently pat them dry. Do not salt them far in advance because salt draws out moisture and can make the noodles limp.

Melt the butter with the olive oil in a large, wide skillet over medium heat. A wide pan gives the zucchini more room and helps moisture evaporate instead of leaving the noodles watery.

Add the minced garlic and cook for about 30 seconds, stirring constantly, just until fragrant. Keep the heat moderate and do not let the garlic brown, as browned garlic can taste bitter in this delicate sauce.

Stir in the drained capers, lemon zest, lemon juice, kosher salt, and black pepper. Cook briefly, stirring, until the butter is aromatic and the ingredients begin to come together.

Add the zucchini noodles and toss continuously for 2 to 4 minutes, until they are just tender but still slightly firm. If your skillet is crowded, cook the noodles in batches so they sauté rather than steam.

Remove the skillet from the heat and toss in the parsley and optional Parmesan. Taste and adjust with more lemon juice, salt, or pepper, then serve immediately while the noodles are glossy and fresh.