Heat a large skillet over medium heat and add olive oil, letting it shimmer.
Add the cubed turkey to the skillet and cook until browned on all sides, about 5-7 minutes, until a golden crust forms and it releases a savory aroma.
Transfer the browned turkey to the slow cooker, along with chopped carrots, diced onion, and celery for added sweetness and depth.
In the same skillet, add minced garlic and cook for about 30 seconds until fragrant, then pour in chicken broth, scraping up any browned bits from the bottom.
Add ground cinnamon and sage to the broth, stirring to combine; cook for about 1 minute to release aromatic flavors.
Pour the spiced broth mixture over the ingredients in the slow cooker, then add canned pumpkin and stir well to combine everything into an even mixture.
Season with salt and pepper to taste, then cover the slow cooker and set it to low. Let it simmer for 6-8 hours until the turkey is tender and the flavors meld beautifully.
Once cooked, open the lid and gently stir the stew. It should be thickened and fragrant, with the vegetables fully cooked and soft.
Taste the stew and adjust seasoning with more salt or pepper if needed, adding a pinch of cinnamon or herbs for extra aroma.
Spoon the stew into bowls, garnish with fresh herbs if desired, and serve hot with crusty bread or a side of your choice.