Put cilantro, spinach and broth in blender and blend until pureed. Add milk and salt and blend until well combined.
Heat olive oil and butter in a large skillet. When butter is melted, add rice and saute until brown (3-4 minutes). Stir constantly. Add onion and garlic and cook for 1 more minute. Add cilantro-spinach mix, stir well, bring to a boil.
Cover, turn heat to low. Cook 20 minutes. Take pan off heat and let rice steam in the covered pan for 10 minutes.
Recipe by Simple as That at https://simpleasthatblog.com/mexican-green-rice-arroz-verde-recipe/