Wipe mushrooms clean with a damp towel or soft brush; avoid soaking. Trim stems as needed and roughly chop larger mushrooms so pieces are roughly uniform, about 1 to 1 1/2-inch pieces for even cooking.

Heat pan

Place a large skillet (preferably stainless steel or cast iron) over medium-high heat. Add olive oil and 1 tablespoon butter and heat until butter melts and starts to foam but does not brown, about 1 minute.

Sear mushrooms

Add mushrooms in a single layer without overcrowding (work in two batches if necessary). Let mushrooms sit undisturbed for 2–3 minutes to brown, then stir or toss and continue to cook, stirring occasionally, until deeply golden and most moisture has evaporated, about 6–8 minutes total per batch.

Aromatics

Push mushrooms to the sides of the pan, add remaining 1 tablespoon butter. Add chopped shallot and sauté 1–2 minutes until softened, then add minced garlic and thyme and cook another 30–45 seconds until fragrant, stirring so garlic doesn't burn.

Deglaze & finish

Pour white wine into the pan to deglaze, scraping up any brown bits from the bottom with a wooden spoon; let the wine reduce by half (about 1–2 minutes). Add stock and simmer 1 minute to marry flavors. Stir in lemon juice, parsley, salt and pepper. Taste and adjust seasoning.

Optional / For Serving

If using, sprinkle grated Parmesan over the mushrooms and stir briefly until slightly melted. Drizzle with truffle oil to taste. Serve hot spooned over crusty bread or alongside as a side dish or topping for steak, pasta, or polenta.