Peel and cube the 6 cups butternut squash, dice the 1 large yellow onion and 2 medium carrots, and chop the 1 medium apple.. Mince the 3 cloves garlic for extra depth.
In a small skillet, heat 1 tablespoon olive oil over medium heat and sauté the onions and garlic for 3–4 minutes, until fragrant. This step adds that classic Ina flavor punch.
Add the sautéed onions, garlic, squash, carrots, and apple into the slow cooker. Pour in the 4 cups chicken broth, then sprinkle in 1 teaspoon fresh thyme leaves, 1 teaspoon salt, and ½ teaspoon black pepper. Give it a quick stir to combine.
Cover and cook on LOW for 6–7 hours or HIGH for 3–4 hours, until the squash and carrots are fork-tender.
Use an immersion blender directly in the slow cooker, or transfer the mixture in batches to a blender. Blend until silky smooth.
Stir in the ½ cup heavy cream (or half-and-half) for richness. Taste and adjust seasoning if needed. Ladle into bowls and top with a drizzle of cream, a sprinkle of thyme, or crunchy croutons for a little texture.