Cook macaroni in salted boiling water.
Make green purée by blending spinach, parsley, roasted jalapeños, and ¼ cup milk.
Make cheese sauce by melting butter in a saucepan, whisking in flour to make a roux.
Gradually whisk in warmed milk until smooth.
Season with salt, pepper, chipotle powder, smoked paprika, and nutmeg.
Stir in grated Gruyère and cheddar cheeses until melted.
Combine green purée with cheese sauce.
Drain cooked macaroni and add to cheese sauce.
Mix breadcrumbs with melted butter.
Top mac and cheese with breadcrumbs.
Bake until golden brown and bubbly.
