Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Cut the chicken breast into 1-inch bite-sized pieces and break the cauliflower into small, uniform florets.
In a large mixing bowl, whisk together the extra virgin olive oil, garlic powder, smoked paprika, sea salt, and black pepper.
Add the chicken pieces and cauliflower florets to the bowl, tossing thoroughly until every piece is evenly coated with the oil and spice mixture.
Spread the chicken and cauliflower in a single layer on the prepared baking sheet, ensuring there is space between the pieces to allow for roasting rather than steaming.
Roast in the oven for 20 to 25 minutes, tossing the mixture halfway through, until the chicken is cooked through and the cauliflower edges are caramelized and crispy.
Remove from the oven, drizzle immediately with fresh lemon juice, and garnish with chopped fresh parsley before serving.