Turn the broiler to high. Set poblano chiles on a baking sheet, and then place the sheet underneath the broiler. Cook, flipping the chiles occasionally with a pair of tongs, until blackened on all sides. Turn off the broiler, and transfer chiles to a plastic bag. Let steam for five to ten minutes. Peel the blackened skins off the chiles, and then remove stems and seeds.
Place roasted poblanos in a blender along with the cilantro, 1 bouillon cube, half of the onion, 2 garlic cloves, crema, and milk. Puree mixture until smooth.
Bring a large pot of water to a boil. Add 1 bouillon cube, the other half of the onion, and 1 garlic clove. Cook the pasta for 10 minutes. When done, drain pasta in a colander and rinse with cold water and discard onion and garlic.
Meanwhile, add butter to large pot set over medium heat. When it foams, pour in the creamy chile mixture. Cook, for about 10 minutes, stirring it occasionally. And season with salt and pepper.
Add the pasta to the pot and toss well for about 5 minutes or until heated through.
Top each serving with a sprinkling of parmesan cheese.