Preheat oven at 180ºC. Line a baking tray with a silicon sheet.
Halve spring roll sheets and put them in batches of 3 on the baking tray. Brush in between and on top of them with butter. Put the tray in the preheated oven and bake for 5 minutes.
Heat 1 tbsp butter each in 2 non-stick pans. Add 1 tbsp chopped garlic each in both pans and sauté till fragrant. Add 1 chopped onion each in both and sauté for 1 minute.
Add mushrooms in pan 1, mix and sauté for 1 minute.
Roughly chop spinach and add to pan 2. Mix and sauté for 1 minute. Add salt and crushed peppercorns, mix well and cook for 1 minute.
Add salt and crushed peppercorns to the mushrooms, mix well and cook for 1 minute.
Place 5 baked spring roll sheet halves stacked on a serving plate. Spread cooked mushroom mixture on it and top with 2 tbsps grated cheese. Place another 5 sheets stacked on it, spread cooked spinach mixture on it and top with remaining cheese. Cover with the remaining sheets stacked on it.