Place the peeled and cubed sweet potatoes, butternut squash, sliced apples, and minced garlic into the slow cooker. Sprinkle the ground cinnamon and nutmeg over the top.
Pour the vegetable broth over the ingredients, ensuring everything is submerged. Cover the slow cooker with its lid.
Set the slow cooker to low and cook for about 6 hours, until the sweet potatoes and squash are very tender and easily mashable, filling the kitchen with warming scents.
Use an immersion blender directly in the slow cooker or transfer the cooked mixture to a blender and puree until smooth and velvety. Be cautious of hot splashes!
Stir in the heavy cream for added richness, then season with salt and pepper to taste. Adjust spice levels if desired.
Pour the hot, creamy soup into bowls, and garnish with a drizzle of cream or fresh herbs if preferred. Serve immediately for a cozy, fall-inspired meal.
