1. Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions, until al dente.
2. Just before draining, remove 1 cup of the pasta cooking water. Drain.
3. Meanwhile, while the pasta cooks, make the pasta sauce.
4. Heat the oil in a large skillet over medium heat. Add the onion and the jalapeño pepper (or Serrano) and sauté until the onion becomes translucent, about 3 minutes.
5. Stir in the garlic and baby spinach and cook tossing with kitchen tongs until the spinach starts to wilt, about 2 minutes. Remove from the heat.
6. Transfer the spinach mixture to a blender. Add the roasted peppers, cilantro, sour cream, chicken bouillon and 2/3 cups of milk or half and half and process until smooth and creamy. Add more milk, if needed.
7. Transfer the poblano pepper mixture to the same pot you used to cook the pasta. Heat over medium-low heat for about 2-3 minutes, stirring as needed.
8. Add half of the cream cheese and stir until it melts. Repeat with the remaining cream cheese. Lower the heat and simmer for about 4 minutes. Season to taste with salt and black pepper.
9. Add the pasta and toss to combine. Add some of the reserved pasta cooking water if needed to make the sauce creamy. Serve garnished with chopped cilantro, crumbled cheese and pepitas, if desired.

To char/roast the peppers:

1. In a Dry Skillet: Heat a cast iron skillet over high heat. Place the peppers in the skillet and char on all sides until blackened.. Use kitchen tongs to turn the peppers as needed. Remove from the stove and proceed to peeling and seeding.
2. On an Open Flame: Put peppers over an open flame, turning them with kitchen tongs, until they blacken on all sides. Proceed to peeling and seeding
3. Under the Broiler: Arrange an oven rack 6 inches from the broiler. Heat the broiler. Place the poblano peppers on a baking sheet lined with aluminum foil. Broil until the tops are blackened and blistered turning the peppers as needed until all sides are blackened. Remove from the oven and proceed to peeling and seeding.
4. Oven Roasted: Preheat the oven to 425ºF. Place the poblano peppers on a baking sheet lined with aluminum foil. Roast until the skins are blackened, about 40 minutes, turning the peppers occasionally for even roasting. Remove from the oven and proceed to peeling and seeding.

Peeling and Seeding:

1. Place the roasted peppers in a paper bag or a resealable plastic bag and close it to keep the steam inside or place the roasted peppers in a bowl and cover the bowl with plastic wrap. Let the peppers steam for about 10 to 12 minutes.
2. Remove the roasted peppers from the bag or bowl and with the help of a piece of paper towel, rub off the skin. The skin should come off quite easily. Slice the peppers from top to bottom to open them up. Remove the stem and then with a piece of paper towel, wipe off the seeds.