Nori Pappardelle with Mussels and Butter

Instructions

1. • 225 g bread flour, plus extra for dusting 
   • 28 g nori powder 
   • 1.5 g kosher salt 
   • 150 g eggs (3 large eggs) plus 40 g egg yolks (2 large yolks) 
   • 5 g teaspoon extra-virgin olive oil
   Whisk flour, nori powder, and 1.5 grams salt together in bowl of stand mixer. Whisk eggs, yolks, and 5 grams oil together in small bowl. Make well in center of flour mixture and pour in egg mixture. Fit stand mixer with dough hook and mix on low speed until dough comes together, 2 to 4 minutes. (If dough doesn’t become cohesive, add up to 30 grams (2 tablespoons) extra water, 5 grams (1 teaspoon) at a time, until dough just comes together.) Increase speed to medium and knead until dough is smooth and shiny, 7 to 10 minutes. Form dough into 9-inch log and wrap in plastic wrap. Let rest at room temperature for at least 30 minutes. (Alternatively, wrapped dough can be refrigerated for up to 24 hours. Let refrigerated dough rest at room temperature for at least 10 minutes or up to 30 minutes before proceeding with recipe.)  
2. Securely clamp pasta machine to counter. To roll out pasta dough, cut dough into 3 equal pieces. Working with 1 piece of dough (keep remaining dough covered with plastic to keep it from drying out), flatten into rectangle and run through rollers set to widest position. Run dough through widest setting 2 more times. Roll pasta thinner by progressively narrowing setting, rolling dough through each setting 2 times. Roll until dough is 1/16 inch thick. If dough gets dry or cracks during rolling, lightly spray with water or dip fingers in water and rub over surface of dough. Cut dough sheet into 12-inch sections. Layer sections on top of each other, dusting with flour between layers to preventing sticking. Cover loosely with plastic and set aside. Repeat with remaining 2 pieces of dough. 
3. Stack 2 sheets of dough. With short side facing you, fold dough into thirds from top to bottom (like a letter). Cut dough at 1-inch intervals into strips of pappardelle. Dust noodles with flour, form into nests, and set aside. Repeat with remaining dough. 
4. • 3,600 g water 
   • 14 g extra-virgin olive oil 
   • 80 g shallots (2 shallots), sliced thin 
   • 10 g garlic (2 cloves), minced 
   • 900 g mussels, scrubbed and debearded 
   • 120 g white wine
   Bring 3,600 grams water to boil in large pot over high heat. Meanwhile, heat 14 grams oil in 12-inch skillet over medium heat until shimmering. Add shallots and garlic and cook, stirring often, until shallots soften and turn translucent, 2 to 4 minutes. Add mussels and wine and increase heat to high. Cover and cook, shaking pan occasionally, until mussels open, 2 to 4 minutes. Transfer mussels to medium bowl, leaving liquid in skillet; turn off heat. (You should have about 225 g (1 cup) liquid left in skillet.) Remove mussels from shells, transfer to small bowl, and cover to keep warm; discard shells.  
5. • 56 g unsalted butter, cut into ½-inch pieces 
   • 18 g kosher salt, plus extra for seasoning 
   • Pepper 
   • 5 g fresh tarragon, chopped fine
   Bring liquid left in skillet to boil over medium-high heat. Gradually whisk in butter, 2 pieces at a time, until sauce is smooth and emulsified, 1 to 2 minutes. Reduce heat to low. Add 18 grams salt and pasta to boiling water in pot and cook, stirring often, until al dente, 1 to 2 minutes. Reserve 112 grams (½ cup) cooking water, then drain pasta and transfer it to skillet with butter sauce. Increase heat to high, add mussels and 56 grams (¼ cup) reserved cooking water, and toss to thoroughly combine. Season with salt and pepper to taste. Adjust consistency with remaining reserved cooking water as needed. Divide pasta among bowls, sprinkle with tarragon, and serve.