Roast and blend the peppers. Heat 2 tablespoons of oil in a skillet over medium heat. Add the chopped ají amarillo peppers and sauté for a few minutes until softened and fragrant. Transfer to a blender and blend until smooth. Add an extra tablespoon of oil if needed to get a silky consistency. Set aside.
Sauté the aromatics. In the same skillet, heat the remaining oil over medium heat. Add the diced onion and cook for 2 to 3 minutes until softened and translucent. Add the minced garlic and cook for another minute or two, stirring so it doesn't burn.
Build the sauce. Pour the blended ají amarillo into the pan and stir to combine. Cook for 1 to 2 minutes, stirring continuously. Add the cream cheese chunks and stir gently until completely melted and the sauce is smooth, golden, and creamy. Season generously with salt and pepper. Keep warm over low heat.
Cook the pasta. While your sauce comes together, bring a large pot of salted water to a boil. Cook the pasta until just al dente according to package directions. Before draining, scoop out about 1 cup (240 ml) of pasta cooking water and set it aside — this is liquid gold for your sauce!
Bring it all together. Drain the pasta and add it directly to the skillet with the huancaína sauce. Toss well to coat every strand. Add splashes of the reserved pasta water as needed to loosen the sauce to a luscious, creamy consistency. Stir in half of the cooked corn kernels and mix gently.
Serve and garnish. Plate the pasta while hot and top with the remaining corn kernels. Finish with a generous shower of sieved hard-boiled egg for that classic Peruvian touch. Serve immediately!
