Toast almonds in skillet over medium heat, stirring constantly until nuts are lightly browned. Remove from heat and set aside.
Melt butter in a large skillet over medium heat. Add onions; sauté until limp and slightly browned at the edge. Add garlic, ginger and Serrano chili; sauté an additional minute. Stir in salt and spices; sauté briefly to blend.
Add chicken; stir and cook until pieces no longer appear pink. Add coconut milk and crushed red pepper. Stir until mixture comes to boil then reduce heat and simmer 20-25 minutes.
Remove from heat and stir in lemon juice. Sprinkle toasted almonds over the top.
Serve over rice and garnish with lemon slices if desired.