Preheat and prep: Heat your oven to 425°F (220°C). Line a large sheet pan with parchment for easy cleanup.
Make the cottage cheese ranch: In a blender or food processor, combine cottage cheese, ranch seasoning, lemon juice, garlic, dill, onion powder, 1 tablespoon olive oil, salt, and pepper.
Blend until smooth and creamy, about 30–60 seconds. Taste and adjust seasoning.
Season the chicken: Pat chicken dry and slice breasts horizontally if very thick so they cook evenly. Sprinkle lightly with salt and pepper.
Coat with sauce: Add about half of the cottage cheese ranch to the chicken and toss to coat.
Reserve the rest for drizzling later.
Prep the veggies: Toss your vegetables with the remaining olive oil, a pinch of salt and pepper. Spread them on the sheet pan, leaving space for the chicken.
Arrange and roast: Place the coated chicken on the pan. Roast for 16–20 minutes, flipping the chicken once halfway through, until the internal temperature reaches 165°F (74°C) and vegetables are tender with browned edges.
Rest and slice: Transfer chicken to a cutting board and rest for 5 minutes.
Slice into strips or cubes.
Assemble meal prep bowls: Divide grains (if using) among meal prep containers. Add roasted vegetables and sliced chicken. Spoon the reserved cottage cheese ranch over the chicken.
Garnish with fresh dill or chives.
Cool before storing: Let containers cool, uncovered, for 15–20 minutes before sealing to avoid excess condensation.