01 - Heat vegetable oil in a large pot or Dutch oven over medium heat. Add the chopped onion and sauté for 3-4 minutes until translucent and softened.
02 - Stir in the minced garlic and grated ginger. Cook for 1 minute until fragrant, taking care not to burn the garlic.
03 - Add the curry powder, cumin, turmeric, chili flakes, and cinnamon to the pot. Cook for 1 minute, stirring constantly, to toast the spices and release their essential oils.
04 - Add the diced tomatoes to the spice mixture. Cook for 2 minutes until the tomatoes begin to break down and soften.
05 - Stir in the cubed butternut squash and rinsed red lentils, ensuring they are well-coated with the spice mixture.
06 - Pour in the coconut milk and vegetable broth. Season generously with salt and black pepper, stirring to combine.
07 - Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 25-30 minutes. Stir occasionally to prevent sticking, cooking until squash is tender and lentils have broken down.
08 - If using, stir in the baby spinach during the last 2 minutes of cooking. Cook until just wilted and vibrant green.
09 - Remove from heat. Taste the curry and adjust seasoning with more salt or pepper if necessary.
10 - Ladle the hot curry into bowls. Garnish with fresh chopped cilantro and serve with lime wedges on the side.