Cut the cauliflower head into bite size pieces and add to a large mixing bowl.
Pour olive oil, 1 teaspoon salt, pepper and garlic powder into the bowl. Mix until coated.
Spread cauliflower on a baking sheet and bake in oven for 30 minutes or until cauliflower is fork tender.
Remove and let cool.
While cauliflower is baking, hard boil the eggs by placing eggs in a pot with water just covering the eggs. Bring to boil, turn off heat and let set for 10-12 minutes. Transfer to bowl of ice water to cool the eggs. [You can skip this step by purchasing pre-packaged hard boiled eggs.]
Place the diced onion, pickle and celery in a medium bowl. Add the cooled cauliflower.