In a large skillet over medium heat add the oil and heat until shimmering. Add the onion and cook for 2-3 minutes or until the onion is tender, stirring often. Add the garlic and cook, stirring constantly for 30 more seconds. Add the other half of the curry powder and garam marsala. Cook, stirring occasionally until fragrant (about 1 minute). Add coconut milk, tomato paste, and chicken broth. Transfer mixture to a 2 cup measuring cup and blend with an immersion blender until smooth.