Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Slice the delicata squash into half-inch thick half-moons, removing the seeds, and halve the brussels sprouts.
Cut the chicken breast into one-inch cubes to ensure they cook at the same rate as the vegetables.
Place the chicken, squash, and brussels sprouts on the prepared sheet pan.
Drizzle with extra virgin olive oil and sprinkle with garlic powder, smoked paprika, sea salt, black pepper, and chopped rosemary.
Toss all ingredients together with your hands or tongs until everything is thoroughly coated in oil and spices.
Spread the mixture into a single layer, ensuring no pieces are overlapping to allow for maximum crispiness.
Roast in the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are golden brown.