In a large pot or Dutch oven heat 1 tablespoon of olive oil over medium high heat. Add the onion to the pot and stir until onion is fully coated with oil. Sauté for approximately 3-4 minutes, stirring occasionally, or until onions just start to soften. Mix the garlic in with the onion and cook for approximately 1 minute, or until fragrant.
Add remaining ingredients- cauliflower, carrots, peas, butternut squash, curry powder, salt and vegetable broth- to the pot and stir. Turn heat to high and bring pot to a boil. Reduce heat to low and simmer, covered, for approximately 20-30 minutes, or until vegetables are fully cooked and fork tender.
Pureé soup until smooth, and completely blended. Be careful not to overfill your blender with hot, boiling, steaming soup (I usually only fill mine half way full and work in several small batches). Return the pureed soup to the stove in a separate pot over low heat.
Taste and add any additional seasonings you see necessary- salt, curry powder, etc. Garnish with a scoop of yogurt, cooked peas and fresh thyme.