1. Preheat oven to 425 degrees Fahrenheit.
2. Slice the zucchinis into strips and cut the leeks in half the long way. Place onto baking sheets, drizzle with olive oil and sprinkle with one teaspoon salt.
3. Roast at 425 degrees Fahrenheit for 30 minutes.
4. Place pot on stove over medium heat. Add roasted zucchinis, leeks, one tablespoon salt, pepper, garlic powder and lemon juice. Fill the pot with water just to the top of veggies.
5. Bring to a boil and then lower flame to simmer for 45 minutes.
6. Add spinach and cook for another 15 minutes.
7. Use an immersion blender to blend until smooth.