1. Heat half of oil in a deep skillet over medium-high heat. Add onion, garlic, ginger, and chile. Cook until onion is soft (about 5 minutes), stirring occasionally. Stir in garam masala, chili powder, and sugar; cook until fragrant (1 or 2 minutes), stirring constantly.
2. Add tomatoes; cook (about 3 minutes), stirring frequently. Add coconut milk and cilantro; cook until mixture comes to a boil, stirring constantly. Reduce heat to simmer; cook until tomatoes break up and mixture thickens (about 20 minutes), stirring occasionally.
3. Preheat oven to 400°. Coat a 9- by 13-inch baking dish with cooking spray. Place remaining oil in a small pan over medium-high heat. Add half of spinach to tomato sauce; cook until wilted (about 3 minutes), stirring frequently. Add remaining spinach; cook until wilted (2-3 minutes), stirring frequently.
4. Spread tomato sauce into dish; spoon chickpeas on top. Sprinkle with salt and pepper. Place cheese evenly over dish. Bake until sauce is bubbly and cheese and beans have browned (20-30 minutes). Remove from oven; serve.