Heat olive oil and butter in a large skillet over medium heat.
Add onions to skillet, and cook until starting to come translucent. and ginger until softened.
Stir in garlic, ginger, and spice blend. Let cook 30 seconds, stirring regularly.
Add chicken to skillet, and season with salt and pepper. Cook, stirring regularly, until chicken is cooked through.
Stir in tomatoes, and bring to a simmer.
Let simmer 5 minutes, stirring regularly.
Remove from heat, and stir in cream.
Serve topped with fresh cilantro, if desired.
Notes
*If you can't find a garam masala blend, use 2 teaspoons garam masala, 1/2 teaspoon smoked paprika, and 1/4 teaspoon cayenne pepper. **Nutrition values are estimates.