1Begin by roasting the three large chile poblanos and one chile jalapeño or serrano until they are nicely charred all around.
2Transfer the roasted chiles to a plastic bag and allow them to sweat for about 5 to 10 minutes.
3After 5 minutes, peel the chiles and remove their stems.
4Transfer the peeled chiles to the blender cup.
5Add a piece of onion, one garlic clove, a handful of cilantro, 4 ounces of cream cheese, 2 cups of crema mexicana, 3/4 of a cup of milk, chicken bouillon, garlic salt, and black pepper to the blender cup with the chiles.
6Blend until the sauce is smooth.
7Set the sauce aside.
8Fill a pot halfway with water and place it over medium-high heat.
9Add a piece of onion, two bay leaves, and salt to the water.
10Bring the water to a boil.
11Once the water boils, add the spaghetti and cook it al dente according to its package instructions.
12Reserve half a cup of the pasta water.
13Drain the spaghetti from the pot.
14Return to the pot over medium heat and melt the butter.
15Once the butter melts, add the sauce.
16Add the reserved pasta water to the sauce.
17Bring the sauce to a simmer.
18Once the sauce simmers, taste it for salt and adjust if needed.
19Add the spaghetti and the cheese to the pot with the sauce.
20Allow the spaghetti, sauce, and cheese to cook together for 5 minutes.