- 4 large portobello mushrooms, each 85 to 115 g
- Extra-virgin olive oil for brushing, plus 1 tablespoon
- 1 very large bunch silverbeet
- ½ cup crumbled feta cheese (about 70 g)
- ½ cup coarsely grated whole-milk mozzarella cheese (about 55 g)
- ¼ cup plus 1/3 cup freshly grated parmesan cheese
- 2 tablespoons mayonnaise
- 2 small spring onions, white and light green parts only, finely chopped (about 3 tablespoons)
- 1 garlic clove, finely chopped
- ⅛ teaspoon ground or freshly grated nutmeg
- ⅓ cup panko (Japanese) breadcrumbs
- Ground black pepper
Barbecuing sturdy greens is easy when you have a perforated pan to keep them from falling between the grill bars. Rinse them well and use the water clinging to the leaves to wilt them. If you can’t find large mushrooms, buy 6 smaller mushrooms and reduce the cooking time.
- Prepare the barbecue for direct cooking over high heat (230° to 290°C). Using a damp paper towel, wipe the outside of each mushroom cap to clean. Using a small knife, cut out the stems.
- Holding 1 mushroom in your palm and using a small spoon, gently scrape out all the black gills, being careful not to tear the delicate cap. (It’s important to remove the gills, as they will discolour the filling during cooking.) Repeat with the remaining mushrooms.
- Brush a large perforated grill pan with oil. Rinse the silverbeet under cold running water. Stack the wet leaves in the prepared pan.
- Grill the silverbeet over direct high heat, with the lid closed, until the greens begin to wilt, 5 to 6 minutes, turning once or twice with tongs. Remove from the grill.
- Cut off the stem at the base of each leaf and discard. Fold the leaves in half lengthways and twist to wring out the excess moisture. Using a large, heavy knife, coarsely chop the greens. You should have a generous 1 cup.
- In a medium bowl mix together the chopped greens, feta, mozzarella, ¼ cup parmesan, the mayonnaise, spring onions, garlic and nutmeg.
- In a small bowl mix together the panko, the remaining ¹/³ cup parmesan and the remaining 1 tablespoon oil. Stir 1 tablespoon of the panko mixture into the greens filling. Season the filling to taste with pepper (about ¼ teaspoon).
- Divide the greens filling evenly among the mushrooms, then pat gently with your hand to fill to the edges.
- Sprinkle the remaining panko mixture evenly over the filling.
- Place the mushrooms on the same grill pan. Grill over direct high heat, with the lid closed, until the cheese melts and the topping is deep brown, 8 to 12 minutes. Using a metal spatula and tongs, transfer the mushrooms to plates and serve.