Heat olive oil in a large skillet over medium-high heat and brown the ground chicken until fully cooked.
Add the butter and diced onion to the skillet, sautéing until the onion is translucent and fragrant.
Stir in the minced garlic, cinnamon, nutmeg, cumin, salt, and pepper, cooking for 1 minute to bloom the aromatic spices.
Transfer the chicken and onion mixture into the slow cooker.
Add the cubed butternut squash, diced potato, sliced carrots, and chicken broth to the slow cooker.
Cover and cook on low for 6 to 7 hours or on high for 3 to 4 hours until the vegetables are fork-tender.
For a creamier texture, use an immersion blender to partially blend the soup, leaving some chunks of chicken and vegetables intact.
Serve warm in large bowls.