Heat the oven to 180°C/200°C fan-forced. Bring a large saucepan of slightly salted water to the boil. Pick and finely chop the rosemary. Peel and crush the garlic. Peel and cut the potatoes into 2cm chunks. Grate the Cheddar cheese. Trim the ends of the green beans.
In a large bowl, mix the beef mince with the crushed garlic, rosemary, Cheddar cheese, fine breadcrumbs, egg 3/4 of the salt and a pinch of pepper. Mix well. Roll the beef into 3cm rissoles and set aside on a plate. You should get 3 rissoles per person.
Add the potatos to the large saucepan of boiling water and cook for 10-12 minutes, or until the potato is soft when pierced with a knife. While the potatoes are cooking, place a colander over the saucepan and add in the green beans. Steam the beans for 2-3 minutes, or until soft. Set aside. Once cooked, drain the potatoes in a colander and return the to the pan. Add in the milk and butter, the remaining salt and a pinch of peppe and mash with a potato masher or fork until smooth. Set aside and cover to keep warm.
Heat a drizzle of olive oil in large frying pan over a medium-high heat. Cook the rissoles in batches for 2-3 minutes on each side, or until browned. Transfer to the oven tray lined with baking paper and bake for 8-10 minutes, or until just cooked through. Tip: Rissoles are cooked when the centre is brown.
Return the frying pan to a medium-high heat and add a drizzle of olive oil. Add the green beans and cook for 2 minutes, or until nicely charred. Season with salt and pepper.
Serve the cheesy beef rissoles on a plate with green beans, and mashed potato. Enjoy!