Adjust rack to middle position and preheat oven to 425 degrees. Place freekeh in a large pot with a pinch of salt and enough water to cover generously. Bring to a boil, then lower heat and reduce to a simmer. Cook until tender, 20-25 minutes. Drain and rinse under cold water.

Wash and dry all produce. Trim Brussels sprouts, then halve lengthwise through stem ends. Slice half the Brussels sprouts into thin shreds. Toss remaining Brussels sprouts halves and squash with a drizzle of olive oil and a pinch of salt and pepper on a baking sheet. Roast in oven until tender, 20-25 minutes, tossing halfway through.

Heat a medium pan over medium heat. Add walnuts and toast, tossing frequently, until fragrant, 2-3 minutes. Remove from pan and set aside.

Heat a drizzle of olive oil in pan used for walnuts over medium heat. Add shredded Brussels sprouts and cook, tossing, until softened, 3-4 minutes. Season with salt and pepper.

Halve and peel shallot, then mince until you have 2 TBSP. Zest lemon until you have 1/2 tsp zest, then halve. Whisk together minced shallot, lemon zest, juice from one lemon half, and 2 TBSP olive oil in a large bowl. Season with salt and pepper. Adjust to taste with more olive oil, if needed.

Core apple, then dice into small cubes. Add freekeh, walnuts, shredded Brussels sprouts, Parmesan, and apple to bowl with dressing and toss to combine. Season with salt and pepper. Divide mixture between plates, then top with roasted veggies and serve.