Preheat the oven to 220C, fan-forced. Peel the potatoes and cut into 2cm chunks. Put the potato in a medium saucepan of cold salted water and bring to the boil. Reduce the heat to medium and cook for 8-10 mins until tender. Drain, then return to the pan. Cover to keep warm.
Step 2 — Roast carrot
While the potato is cooking, line an oven tray with baking paper. Cut the carrots into 2cm-thick batons. Crush or finely chop the garlic. Put the carrot and garlic on the lined tray, drizzle with 1 tbs olive oil, season with salt and pepper and toss to coat. Roast for 15-20 mins until golden and tender.
Step 3 — Start pie filling
Meanwhile, finely chop 1 tsp rosemary leaves*, discarding the stems. Heat 2 tsp olive oil in a separate medium saucepan over medium heat. Add the country seasoning and rosemary and cook, stirring, for 1 min or until fragrant. Add the beef bolognese and worcestershire sauce and bring to the boil, stirring, for 2 mins or until heated through.
Step 4 — Finish pie filling
Add the peas to the beef bolognese mixture, return to the boil and cook for a further 1 min. Stir in the spinach until wilted. Transfer the beef mixture to a 1.25L (5 cup) ovenproof dish. Put the tray with the carrot on the bottom oven shelf and turn the oven to the grill mode.
Step 5 — Make cheesy mash
Mash the potato until smooth. Add the cheese and 20g butter and stir to combine. Taste, then season with salt and pepper.
Step 6 — Get ready to serve
Spread the cheesy mash over the beef mixture, then run a fork over the top to create ridges (the rough surface will help the mash to brown). Put the dish on an oven tray. Grill for 6-8 mins until golden. Divide the cottage pie and roast carrot among plates to serve.