Step 1: Cook the Spaghetti
Bring a large pot of salted water to a boil.
Add 1 pound of dry spaghetti and cook until just barely al dente, following the package instructions.
Drain the pasta and set aside.
Step 2: Toast the Panko Breadcrumbs
Melt 2 tablespoons of unsalted butter in a large, high-sided skillet over medium heat until foaming.
Add 1 cup of panko breadcrumbs and cook, stirring occasionally, until they are golden and fragrant (about 3–4 minutes).
Transfer the toasted breadcrumbs to a small bowl and set aside.
Step 3: Make the Brown Butter Sauce
Wipe out the skillet with a paper towel to remove any leftover breadcrumbs.
Add the remaining 8 tablespoons of butter to the skillet over low heat. Stir continuously with a wooden spoon to melt the butter evenly.
As the butter melts, it will foam and develop brown bits at the bottom. Once the butter turns golden brown and has a nutty aroma (about 3–5 minutes), add the minced garlic and red pepper flakes.
Stir constantly for 2 minutes, being careful not to let the garlic burn.
Step 4: Combine the Pasta and Sauce
Add the cooked spaghetti to the skillet with the brown butter sauce.
Sprinkle 1 cup of grated Parmesan cheese over the pasta.
Use tongs to toss everything together until the pasta is fully coated in the sauce and the cheese is melted.
Step 5: Add the Finishing Touches
Add the reserved toasted panko breadcrumbs, 2 tablespoons of lemon juice, and 2 tablespoons of chopped parsley to the skillet.
Toss gently to combine all the ingredients.
Step 6: Serve and Enjoy
Divide the pasta into bowls.
Garnish with additional Parmesan cheese, parsley, and a sprinkle of red pepper flakes, if desired. Serve immediately and enjoy!