Bring a large pot of water to a rolling boil and add 1 tablespoon kosher salt. Use abundant water so the pasta moves freely — salted water seasons the pasta from the inside and is the foundation of the dish. If using fresh tagliatelle, cook 2–3 minutes until al dente; if using dry, follow package directions (typically 7–9 minutes) and aim for firm-to-the-bite.

While the water heats, pat the scallops dry on both sides with paper towels and season lightly with salt and cracked black pepper. Removing surface moisture is essential to achieve a golden sear rather than steaming the scallops.

Heat a large skillet (preferably stainless steel or cast-iron) over medium-high heat until very hot. Add the 1 tablespoon olive oil and swirl. Place scallops in the pan spaced at least 1 cm apart — crowding lowers the pan temperature and prevents browning. Sear scallops without moving them for 1½–2 minutes until a deep golden crust forms, then flip and sear the other side 30–60 seconds until just cooked through (they continue to cook off heat). Transfer scallops to a plate and loosely tent with foil to rest.

If your rehydrated mushrooms came with any soaking liquid, strain it through a coffee filter or fine mesh and reserve up to 1–2 tablespoons — it’s pure umami and can lift the sauce. Squeeze excess water from the mushrooms so they will brown instead of stewing.

In the same skillet over medium heat, add 1 tablespoon of olive oil if the pan is dry. Add the smashed garlic and sauté briefly (20–30 seconds) to infuse the oil — you want fragrant garlic without browning it, which makes it bitter. Add the squeezed mushrooms and a pinch of salt and cook, stirring, until they begin to take on color, about 3–4 minutes; browning concentrates flavor.

Push mushrooms to one side; lower heat to medium-low and add the 30 g unsalted butter to the cleared space. Allow the butter to melt, foam, then turn a deep nutty-golden brown (3–4 minutes). Watch carefully and stir — browning the milk solids develops the toasty, caramel notes that define brown-butter sauce. When the butter starts to brown, add the sage leaves so they crisp and release aromatic oils into the butter (15–30 seconds). Remove and discard the garlic clove.

When the pasta is al dente, reserve ½–1 cup of starchy pasta cooking water, then drain the pasta. Add the drained pasta directly to the skillet with the browned butter and mushrooms. Toss vigorously, adding a splash of the reserved pasta water as needed to emulsify the sauce — the starch in the water helps create a silky coating on the noodles and binds the butter to the pasta.

Stir in the lemon zest and season with salt and freshly cracked black pepper to taste. Taste and adjust: a few drops of the reserved mushroom soaking liquid (if used) or another splash of pasta water can intensify umami and loosen the sauce.

Divide pasta between two warmed plates. Arrange the seared scallops on top (3–4 each), spoon any resting juices into the sauce, and top with the crisped sage leaves. The hot pasta and butter will rewarm the scallops gently while preserving their crust.

Finish with a light drizzle of extra-virgin olive oil and a final grind of black pepper. Serve immediately — the interplay of warm brown butter, bright lemon, and tender scallops is best enjoyed right away.