Preheat your oven to 400°F (200°C).

In a large bowl, combine the chopped onion, zucchini, apple and sweet potatoes. Drizzle with 1 teaspoon of vegetable oil and add the minced garlic. Toss everything together until the vegetables are evenly coated with oil and garlic.

Spread the vegetable mixture on a large baking sheet in a single layer. Make sure the vegetables aren't overcrowded to ensure even roasting.

Place the baking sheet in the preheated oven and roast for about 25-30 minutes, or until the vegetables are tender and lightly caramelized. Stir once halfway through cooking to ensure even browning.

Once the vegetables are roasted, remove them from the oven and let them cool slightly for about 5 minutes.

Transfer the roasted vegetables to a large pot. Add 3 cups of the chicken broth and bring the mixture to a simmer over medium heat.

Using an immersion blender, carefully blend the vegetables and broth until smooth. If you don't have an immersion blender, you can transfer the mixture in batches to a regular blender, being careful when blending hot liquids.

Once the soup is smooth, stir in the skim milk and the remaining 1 cup of chicken broth. Adjust the consistency to your liking by adding more broth if you prefer a thinner soup.

Season with salt and pepper to taste. Remember, the amount of salt needed will depend on the saltiness of your chicken broth.

Simmer the soup for an additional 5-10 minutes to ensure all flavors are well combined and the soup is heated through.

Serve the soup hot, garnished with a sprinkle of chopped peanuts on top for added crunch and flavor.

For storage, let the soup cool completely before transferring to airtight containers. It will keep in the refrigerator for up to 5 days or in the freezer for up to 3 months.