Begin by chopping the butternut squash into cubes, slicing the carrots, and dicing the potatoes. Arrange all the prepared vegetables on your cutting board, ready to load into the slow cooker.
Add the chopped vegetables into the bowl of the slow cooker. Pour in the vegetable broth, making sure the vegetables are mostly submerged.
Sprinkle the ground cumin and smoked paprika over the vegetables. Season generously with salt and freshly ground black pepper.
Cover the slow cooker with its lid and set it to low. Let the soup simmer for about 6 hours, or until the vegetables are fork-tender and the flavors have melded into a fragrant broth.
Once cooked, remove the lid and use an immersion blender directly in the pot to blend the soup until smooth and velvety. Alternatively, carefully transfer the soup to a blender in batches and blend until smooth, then return to the slow cooker.
Taste the soup and adjust seasoning with more salt, pepper, or spices if desired. Give it a gentle stir to incorporate any adjustments.
Ladle the vibrant, thick soup into bowls. The final texture should be smooth with a warm, inviting aroma of spices and roasted vegetables.