Preheat oven to 400 F, cut butternut squash in half and lay it facing downward on a pan covered in foil. Cook for 40 minutes.
In a large pot, drizzle oil and add onion, garlic, and ginger. Cook until the onions are clear, stirring often.
Pour in the milk, broth, and lentils, and stir. Bring to a boil over medium-high heat and then reduce heat, cover and simmer for 20 minutes, until lentils are cooked through.
When the squash is finished cooking, remove from oven, spoon out and discard seeds. Then scoop out the flesh and place in a high-powered blender.
Add half of the soup mixture into blender and puree until smooth. Pour back into the soup pot.
Stir in the baby spinach and simmer until the spinach is wilted.
Divide into bowls, serve, and enjoy!