SOAK bread in evaporated milk and 1/2 cup water in small bowl. Place chayote in medium pot with salt and remaining 1 cup water. Cover; cook on low heat about 25 to 30 minutes or until just tender, stirring occasionally. Drain; set aside. Stir Media Crema into bread mixture.
MELT butter in large skillet on medium heat. Add garlic, tomato, pepper and onion. Cook for about 4 minutes. Add chayotes and reserved soaked bread mixture. Stir in annatto. Cook on low heat for 20 to 30 minutes, stirring occasionally. Season with salt and pepper to taste. Serve over hot rice.
VARIATION: For Guiso de Pipian, substitute 2 1/2 cups chopped zucchini (about 2 medium) for chayote. Follow recipe as directed, but cook zucchini in salt and water for about 15 minutes, instead of 25 to 30 minutes.