Rinse chicken and pat dry with paper towels, then cut each piece in half and place in a large bowl.
Remove cauliflower stalks and cut into equal sized chunks and place in a large bowl.
Mix together garlic powder, lemon zest, salt, pepper, olive oil, lemon juice and parsley and then pour half on top of the chicken and the other half on top of the cauliflower.
Toss and rub cauliflower and chicken to ensure each piece is well coated.
Set coated chicken aside in the fridge.
Scatter cauliflower onto sheet pan and then place sliced shallots among the cauliflower chunks.
Place in a preheated oven at 425 and cook for 15 mins.
Remove sheet pan from oven and shake cauliflower and shallots free, then turn as many chunks as is possible.
Add chicken in amongst the cauliflower and shallots then return to the oven and cook for 10 mins.
Remove sheet pan from oven again and turn chicken pieces and return to oven and cook for a further 10-15 mins.
Remove sheet pan from oven and test that all ingredients are appropriately cooked through.
Once ready to serve, place on top of a green salad, drizzle with truffle oil and freshly squeezed lemon juice.