Step 1: Cook the Pasta : Bring a large pot of salted water to a boil. Add pasta and cook until al dente according to package instructions. reserve about ½ cup of the pasta water, then drain and set aside.

Step 2: Cook the Shrimp : In a large skillet, heat olive oil and 1 tbsp of butter over medium-high heat. Add shrimp and cook for 1–2 minutes on each side until pink and opaque. Remove shrimp from the pan and set aside.

Step 3: Build the Miso Butter Base ; In the same skillet, add the remaining 1 tbsp butter. Sauté garlic and shallot for 1–2 minutes until fragrant and translucent. Stir in the miso paste, breaking it up with your spatula until it blends smoothly into the butter.

Step 4: Make the Creamy Sauce : Lower the heat to medium-low. Pour in heavy cream and stir until the miso butter dissolves into the cream. Add Parmesan cheese and soy sauce (if using), stirring until the sauce thickens slightly.

Step 5: Combine Everything : Add the cooked pasta to the sauce and toss to coat evenly. Gradually add reserved pasta water until the sauce reaches your desired consistency — creamy and glossy. Return the shrimp to the pan and toss gently to warm through. Squeeze in lemon juice and add a pinch of zest for brightness.

Step 6: Adjust and Serve : Taste and season with salt and pepper as needed. Serve hot, topped with chopped parsley, extra Parmesan, and red pepper flakes if desired.