Combine water and bouillon in a large glass measuring cup; stir to dissolve.
Place spinach, cilantro and bouillon mixture in a blender; cover. Blend until smooth. Add evaporated milk; pulse until well combined.
Heat butter and oil in a large skillet over medium-low heat until butter is melted. Stir in rice; cook, stirring frequently, for 4 minutes. Add onion and garlic; cook for 1 minute. Add spinach/cilantro mixture; increase heat to medium. Stir well and bring to a boil. Cover; reduce heat to low. Cook for 20 minutes.
Stir rice carefully. Cover and cook for an additional 2 minutes. Remove from heat. Keep covered and let rest for 10 minutes before serving.