Preheat the oven to 400ºF. Rinse and dice the potatoes into 1/2" cubes.
In a medium bowl, combine the 1/3 cup Parmesan, 1/2 tsp garlic powder, 1/4 tsp paprika, and 1/4 tsp salt with the diced potatoes. Drizzle 1 Tbsp cooking oil over the seasoned potatoes, then toss until evenly coated.
Line a medium-large sized baking sheet with parchment paper, spread the potatoes evenly across the sheet, then transfer to the oven. Roast in oven for 30 minutes, or until golden brown and crispy, carefully stirring once halfway through, to better brown the potatoes.
Wash and chop the broccoli into florets, then place in a bowl and drizzle with 1 Tbsp vegetable oil & add 1/4 tsp of salt + pepper. Toss until the broccoli is evenly coated.
Spread the broccoli out onto a parchment-lined baking sheet and roast in the oven for about 20 minutes, or until lightly browned on the edges, stirring once halfway through.
While the vegetables are roasting, prepare the chicken. Fillet the chicken breast into two thinner pieces to help them cook faster and more evenly*. Combine the 1 Tbsp ranch seasoning, 1/4 tsp onion powder, 1/4 tsp garlic powder, 1/4 tsp paprika, 1/2 tsp cajun seasoning (optional), in a small bowl & mix. Sprinkle evenly across both sides of your chicken breasts, then season with salt + pepper to taste.
Heat a large skillet over medium heat and once hot, add 1 Tbsp vegetable oil and swirl to coat the surface. Add the chicken breasts and cook for about 5-6 minutes on each side or until golden brown on both sides + cooked through.
Remove the chicken to a cutting board to rest for 5 minutes. Once the chicken has had a moment to rest, carefully slice the chicken breast into strips.
Evenly divide the roasted potatoes, broccoli, and sliced chicken between your 4 meal prep containers. Optional - fill 4 small dressing containers with around 1-2 Tbsp ranch dressing each for dipping or drizzling over your meal. Refrigerate until ready to heat & serve!