1.Coarsely grate kumara; squeeze out excess liquid. Combine kumara with breadcrumbs, grated parmesan, egg, half the garlic and 1 tablespoon of the oil in a large bowl; season.
2.Line a 24cm (9½-inch) non-stick frying pan with baking paper. Add kumara mixture, pressing down firmly and evenly to cover base of pan; cook, covered, over medium heat 10 minutes or until browned underneath and kumara is almost tender. Slide rösti onto a flat plate; invert pan over rösti then turn pan and rösti over. Cook further 8 minutes or until rösti is browned underneath and cooked through.
3.Meanwhile, preheat oiled grill pan (or barbecue).
4.Stir butter, herbs and remaining garlic in a small saucepan, over low heat, until just melted.
5.Peel mushrooms; trim stalks to 1cm (½-inch). Brush a little of the butter mixture on both sides of mushrooms; season. Cook mushrooms in grill pan, 2 minutes each side or until browned and tender.
6.Cut rösti into wedges and divide between plates; top with spinach and mushrooms, then drizzle with remaining butter mixture. Top with shaved parmesan; serve with lemon wedges.
Kumara turns brown when cut so it’s best to grate it just before you use it. If you have a scratch-free non-stick pan, you won’t need to line it with baking paper.Note