Peel potato and cut into 2cm chunks. Put in a medium saucepan, cover with cold salted water and bring to the boil. Coarsely chop cauliflower stem, then cut the head into small florets. Crush or finely chop garlic. Juice half the lemon and cut remaining lemon into wedges. Crumble 1 stock cube* into a heatproof jug, add 125ml (½ cup) boiling water and stir to dissolve.
Step 2 — Make mash
When the potato comes to the boil, add the cauliflower and cook for 10 mins or until tender. Drain well and return to the pan. Mash the potato and cauliflower until smooth. Add 1 tbs milk and stir until combined. Taste, then season with salt and pepper. Cover to keep warm.
Step 3 — Finish prep
Meanwhile, combine the Italian seasoning and 1½ tbs flour in a shallow dish. Put the chicken flat on a board, put your hand on top and halve horizontally into fillets. Dust the chicken with the flour mixture and shake off the excess.
Step 4 — Fry chicken
Heat 1 tbs olive oil in a medium deep frypan over medium-high heat. Cook the chicken for 2-3 mins each side until golden and almost cooked through. Remove from the pan.
Step 5 — Make sauce
Heat the garlic and 20g butter in the same pan over medium heat. Add 2 tsp flour and cook, stirring, for 2 mins or until foaming. Gradually add the stock, stirring constantly to prevent lumps forming. Bring to a simmer and cook, stirring, for 2 mins or until thickened. Stir in 2 tsp lemon juice*. Taste, then season with salt and pepper.
Step 6 — Get ready to serve
Add the peas, chicken and any resting juices to the sauce and cook, covered, for 2 mins or until the chicken is cooked through. Coarsely chop the parsley leaves, discarding the stems. Divide the mash and chicken and pea piccata among plates. Scatter with the parsley and capers (you can leave them out if you prefer) and serve with the lemon wedges.