Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente.

Just before draining, remove 1 cup of the pasta cooking water. Drain the pasta and set it aside.

While the pasta cooks, heat the olive oil in a large skillet over medium heat.

Add the chopped onion and jalapeño (or serrano) pepper, and sauté until the onion becomes translucent, about 3 minutes.

Stir in the minced garlic and spinach leaves. Cook while tossing with kitchen tongs until the spinach starts to wilt, about 2 minutes. Remove from heat.

Transfer the spinach mixture to a blender. Add the roasted poblano peppers, cilantro, sour cream, chicken bouillon, and 2/3 cup of milk or half and half. Blend until smooth and creamy. Adjust with more milk for desired consistency.

Pour the poblano pepper mixture back into the pot you used for the pasta. Heat over medium-low for about 2-3 minutes, stirring as needed.

Add half of the cream cheese and stir until it melts, then repeat with the remaining cream cheese. Lower the heat and let it simmer for about 4 minutes. Season with salt and black pepper to taste.

Add the cooked pasta and toss to combine. Use some of the reserved pasta cooking water if needed to make the sauce creamier.

Serve warm, garnished with chopped cilantro, crumbled cheese, and pepitas if desired.