Peel, then cut sweet potatoes into 1-inch pieces. Add sweet potatoes, 1 tsp (2 tsp) salt and enough water to cover (by approx. 1-2 inches) to a large pot. Cover and bring to a boil over high heat. Once boiling, reduce heat to medium. Simmer uncovered until sweet potatoes are fork-tender, 10-12 min.
Meanwhile, core, then cut pepper into ½-inch slices. Trim green beans. Combine breadcrumbs and Parmesan in a shallow dish.
Add peppers, green beans and 1 tbsp (2 tbsp) oil to a parchment-lined baking sheet. Season with salt and pepper, then toss to combine. Roast in the middle of the oven until veggies are tender-crisp, 14-17 min.
Meanwhile, pat chicken dry with paper towels. Carefully slice each piece of chicken in half through the centre, parallel to the cutting board. (NOTE: You will have 4 pieces of chicken for 2 ppl and 8 pieces for 4 ppl.) Coat chicken all over with mayo. Working with one piece of chicken at a time, firmly press both sides into breadcrumb mixture to coat completely.
Heat a large non-stick pan over medium heat. When hot, add 1 tbsp oil, then chicken. Pan-fry until golden-brown, 2-3 min per side. (NOTE: Don't overcrowd the pan. Cook in batches for 4 ppl, using 1 tbsp oil per batch). Transfer chicken to another parchment-lined baking sheet. Roast in the top of the oven until cooked through, 5-6 min.**
When sweet potatoes are fork-tender, drain and return them to the same pot, off heat. Mash 2 tbsp (4 tbsp) butter and 2 tbsp (4 tbsp) milk into potatoes until smooth. Season with ⅛ tsp (¼ tsp) salt and pepper, to taste. Divide sweet potato mash, Parmesan chicken and roasted veggies between plates.
If you've opted to get chicken breasts, cook them in the same way the recipe instructs you to cook the pork chops.**