Heat olive oil in a pan over medium high heat.
Add garlic and onion, and cook, stirring for 2-3 minutes.
Stir in coconut milk, tomato paste, flour, garam masala, curry powder, chili powder and ginger powder until well combined and slightly thickened, about 1-2 minutes
Add salt and pepper, to taste.
Place chicken into slow cooker.
Add the sauce and combine.
Cover and cook on low heat for 5 hours.
Add the cilantro in the last hour