For the Onions and Garlic - In a large skillet add olive oil. Heat the skillet on low to medium heat and add the chopped onions and stir. Add the chopped garlic and stir.
Continue stirring until the onions start to turn translucent (about 6 minutes). If the garlic is cooking too fast (starting to turn a golden color), turn the heat down a little.
Remove the pan from the heat and set aside.
For the Soup Ingredients - To the slow cooker pot, add the squash, apple, carrot, onion, garlic, cinnamon, curry powder, salt, pepper, red pepper flakes and broth.
Stir all ingredients together until combined.
Cooking the Soup - Cover with a lid and cook on the low setting for 8 hours (or the high setting for 4 hours).
Blending the Soup - After the soup is cooked and while it's warm, use an immersion blender to blend the soup until smooth.
If an immersion blender isn't available a regular blender with a pitcher that's made for hot ingredients can be used. Using a ladle, carefully transfer the hot soup into the blender (please see below for more details).If Using a Blender to Blend the Soup:Blending the Hot/Warm Ingredients - When using a blender for hot liquids it’s very important to use caution; since the ingredients are hot, steam can build up and blow the lid off of the blender.Here are some tips when using a blender for hot liquids:– add the soup to the blender jar in batches that are no larger than 1/3 full– remove the center piece from the blender lid– place the lid (minus the center piece) on the blender jar– cover the lid with a clean towel folded to a size slightly larger than the lid– hold the towel over the lid while blending on the lowest speedAfter blending the soup until creamy, transfer it from the blender pitcher back into the slow cooker pot.
To the warm soup, add half and half, and coconut milk. Stir together until combined. Do a quick taste test and add more salt if needed.
Serve while warm.