Bring a medium saucepan of water to a boil. Add the tomatillos and jalapeño and cook until softened, about 10 minutes. Transfer to a blender using a slotted spoon; add the cilantro stems, 1 1/2 cups tortilla chips, a big pinch each of salt and pepper and 1/2 cup water. Blend until smooth.
Meanwhile, heat the olive oil in a large broiler-proof nonstick skillet over medium-high heat. Add the onion, poblano and a pinch each of salt and pepper; cook, stirring occasionally, until lightly browned, 6 to 7 minutes. Gradually add the spinach, stirring to wilt before adding more; cook until all the spinach is wilted, then season with salt and pepper. Pour the sauce from the blender into the skillet and stir to combine. Reduce the heat to maintain a gentle simmer.
Preheat the broiler. One at a time, crack each egg into a small bowl, make a well in the sauce and add the egg to the well. Drag the edge of a rubber spatula through the egg whites (don’t break the yolks). Season with salt and pepper and cook until the egg whites are just starting to set, 12 minutes. Transfer the skillet to the broiler and cook until the egg whites are set, 1 to 2 minutes.
Meanwhile, thin the sour cream with 1 to 2 tablespoons water; season with salt and pepper. Drizzle over the eggs and sprinkle with the cilantro leaves. Serve with the remaining tortilla chips.