Peel the potatoes and cut into 4cm chunks. Put the potato in a medium saucepan, cover with cold salted water and bring to the boil. Reduce the heat to medium and cook for 12-14 mins until tender. Drain and return to the pan.
Step 2 — Prep ingredients
While the potato is cooking, preheat the oven to 200C, fan-forced. Finely grate the parmesan. Finely chop the carrot and onion. Strip the thyme leaves, discarding the tough stems. Drain the beef brisket, reserving the liquid. Cut the brisket into bite-sized chunks.
Step 3 — Make pie filling
Heat 1 tsp olive oil in a medium frypan over medium-high heat. Cook the carrot, onion and thyme, stirring occasionally, for 4 mins or until softened. Add the brisket, gravy powder, reserved brisket liquid and 2 tbs water and cook, stirring, for 2 mins or until the gravy boils and thickens. Transfer to a 1L (4 cup) baking dish.
Step 4 — Mash potato and cook pie
Mash the potato until smooth. Add the parmesan and 10g butter and stir to combine. Taste, then season with salt and pepper. Spread the mash over the pie filling to cover, then use a fork to create a textured finish (this will help it to crisp). Bake the pie on the upper oven shelf for 20 mins or until bubbling.
Step 5 — Toast walnuts
While the pie is baking, put the walnuts on an oven tray and bake on the lower shelf for 4 mins or until toasted. Set aside to cool slightly.
Step 6 — Toss salad and serve
Meanwhile, whisk 2 tsp extra virgin olive oil, 1 tsp red wine vinegar, ½ tsp dijon mustard and ½ tsp honey in a large bowl until combined. Season with salt and pepper. Add the spinach and walnuts to the dressing and toss to combine. Serve the cottage pie at the table with the spinach and walnut salad.