Soy Butter Mushroom Pasta (Japanese Wafu Spaghetti, 30 Minutes)

This soy butter mushroom pasta is Japanese wafu spaghetti at its simplest and best: spaghetti tossed with deeply browned mushrooms in a glossy sauce of butter and soy sauce, finished with garlic, green onions, and a snowfall of shredded nori. It tastes like something from a tiny Tokyo cafe, but it uses pantry staples and takes 30 minutes from start to finish.

If you love quick, savory pasta dinners, pair this with Creamy Garlic Parmesan One-Pan Pasta for an Italian night and Creamy Pumpkin Pasta for a cozy fall rotation.

Why This Recipe Works

• Browning the mushrooms first is everything: A hot, uncrowded pan gives the mushrooms crisp golden edges and deep umami instead of a steamy, gray pile.
• Butter and soy are a perfect pair: The butter rounds out the soy sauce’s saltiness into a glossy, savory coating that clings to spaghetti without any cream.
• Pasta water makes the sauce: Starchy cooking water emulsifies the butter and soy into a silky sauce that coats every strand.
• Nori adds the wafu signature: Shredded seaweed on top gives a toasty, oceanic note that makes the dish taste unmistakably Japanese.

Ingredients

• 12 oz (340 g) spaghetti
• 1 lb (450 g) mixed mushrooms (shiitake, shimeji, and cremini), sliced or torn
• 4 tablespoons (55 g) unsalted butter, divided
• 3 tablespoons (45 ml) soy sauce
• 1 tablespoon (15 ml) mirin (optional)
• 3 cloves garlic, thinly sliced
• 1 tablespoon (15 ml) neutral oil
• 1/2 teaspoon (1 g) black pepper
• 4 green onions, thinly sliced
• 1 sheet nori, shredded, for topping (optional)
• Grated Parmesan, for serving (optional)

(full list in card)

Photo note: the second image shows mushroom pasta with wide ribbon pasta and olives, which differ from this recipe’s spaghetti; the primary photo shows the recipe as written.

How to Make Soy Butter Mushroom Pasta

Step 1: Cook the spaghetti

Bring a large pot of salted water to a boil and cook the spaghetti until 1 minute shy of the package directions. Reserve 1 cup (240 ml) of the pasta water, then drain.

Step 2: Brown the mushrooms

Heat the oil in a large skillet over medium-high heat. Add the mushrooms in a single layer, in batches if needed, and cook without stirring for 3 to 4 minutes per side until deeply golden. Season with pepper and set aside.

Step 3: Build the soy butter sauce

Reduce the heat to medium, melt 2 tablespoons of butter in the same skillet, and cook the garlic for 1 minute until fragrant. Add the soy sauce and mirin, if using, and simmer for 30 seconds, scraping up the browned bits from the pan.

Step 4: Toss and serve

Add the spaghetti, mushrooms, remaining butter, and a splash of pasta water to the skillet. Toss vigorously for 1 to 2 minutes until the sauce turns glossy and coats the pasta, adding more pasta water as needed. Serve topped with green onions, shredded nori, and Parmesan if using.

Tips

• Do not crowd the pan: Mushrooms steam instead of browning if they are piled up, so brown them in two batches if your skillet is small.
• Salt lightly at first: Soy sauce brings plenty of salt, so season the mushrooms with pepper only and adjust salt at the very end.
• Use the pasta water generously: It is the difference between a greasy butter slick and a silky sauce, so add it a splash at a time until the pasta shines.
• Tear, do not slice, delicate mushrooms: Shimeji and oyster mushrooms tear into natural pieces that catch more sauce than neat slices do.

Storage

Refrigerate leftovers in an airtight container for up to 3 days. Reheat gently in a skillet with a splash of water and a knob of butter to bring the sauce back to life; the microwave works but can make the pasta gummy. Do not freeze, as the mushrooms turn rubbery on thawing.

Frequently Asked Questions

What is wafu pasta?

Wafu means Japanese-style, and wafu pasta pairs Italian pasta with Japanese seasonings like soy sauce, butter, mushrooms, and nori. It is a staple of Japanese cafes, where spaghetti gets treated with the same care as a noodle dish.

Which mushrooms work best?

A mix is best: shiitake for deep umami, shimeji for delicate texture, and cremini for meaty bulk. If you can only find one kind, cremini alone still makes an excellent dish.

Can I make this vegan?

Yes. Use a good plant-based butter and skip the Parmesan; the soy butter sauce itself is already dairy-free once the butter is swapped. Check that your mirin is vegan if you use it.

What if I do not have mirin?

Skip it. The mirin adds a touch of sweetness and gloss, but the dish works perfectly with just butter and soy sauce; add a pinch of sugar if you miss the sweetness.

Recipe Card

Recipe: Soy Butter Mushroom Pasta. Prep: 10 minutes | Cook: 20 minutes | Total: 30 minutes | Servings: 4 | Calories: 540 per serving (estimated).

Ingredients (US + metric): as listed above.

Instructions: 1. Boil the spaghetti in salted water until 1 minute shy of the package directions; reserve 1 cup (240 ml) of pasta water, then drain. 2. Brown the mushrooms in oil over medium-high heat in a single layer, 3 to 4 minutes per side, until deeply golden; season with pepper and set aside. 3. Melt 2 tablespoons of butter in the same skillet over medium heat, cook the garlic for 1 minute, then add the soy sauce and mirin and simmer for 30 seconds, scraping up the browned bits. 4. Add the spaghetti, mushrooms, remaining butter, and a splash of pasta water; toss for 1 to 2 minutes until glossy, adding more pasta water as needed. Serve with green onions, nori, and Parmesan if using.

Notes: Nutrition (estimated per serving): 540 calories, 16 g fat, 82 g carbohydrates, 5 g fiber, 4 g sugar, 16 g protein, 980 mg sodium. Values are estimates and will vary with the exact ingredients used.

Keywords: soy butter mushroom pasta, wafu mushroom spaghetti, japanese mushroom pasta, soy sauce butter pasta, butter shoyu pasta.