Heat a large pot over medium high heat. Add ½ cup of chopped yellow onion and cook it for about 5 minutes until it’s soft. Stir it around a bit so it doesn’t burn. Now, add 2 minced garlic cloves and cook for another minute. Just until it smells super fragrant.
Add the peeled and diced russet potato (about 3 cups) and cook for about 3-4 minutes, stirring now and then.
Next, throw in the 2 lbs of zucchini (about 4-5 zucchinis sliced into half-moons). Give it a little splash of the broth and cook for another 5 minutes, stirring occasionally. It’ll start to soften and get all juicy.
Pour in your 2 ½ cups vegetable broth, then sprinkle in 1 tsp salt and ½ tsp black pepper. Give it a good stir, cover the pot, and let it simmer for about 10-12 minutes. You’re looking for the zucchini and potatoes to be tender.
Lastly, stir in ½ cup baby spinach. Let it cook for a minute until it wilts into the soup. This will add a beautiful bright green color and a bit more nutrition to the soup.
Time to make it all smooth and creamy! Pour half of the soup mixture into a high speed blender and blend until creamy (careful as hot air will want to release out of the top lid).
Then repeat with the last half of the soup. Note: Be sure to blend in two separate batches or the blender may overflow! You can also use an immersion blender and blend the soup right in the pot or even a food processor.