Combine chicken, onions, garlic, raisins, 1 teaspoon of the garam masala, 1/4 teaspoon of the salt, the pepper and broth in slow cooker bowl. Cover and cook for 3 hours on HIGH or 5 hours on LOW.
In a small bowl, stir together the remaining 3/4 teaspoon garam masala, remaining 1/4 teaspoon salt, the yogurt and cornstarch. Remove chicken to a platter and keep warm.
Whisk yogurt mixture into slow cooker bowl and cover; cook an additional 15 minutes or until sauce has thickened. Stir in almonds and serve sauce with chicken over rice, if desired.