Step 1

Preheat oven to 200°C/400°F. Line three oven trays with baking paper.

Step 2

Place mushrooms cup-side up, on two trays. Drizzle with 2 tablespoons of the oil; season. Place eggplant on remaining tray. Drizzle with ¼ cup of the remaining oil. Roast mushrooms and eggplant for 35 minutes.

Step 3

Meanwhile, make rocket and walnut pesto.

Step 4

Place fetta slices on an oven tray. Place under hot grill (broiler) for 5 minutes or until browned lightly.

Step 5

Toss tomatoes in remaining oil and the vinegar in a medium bowl.

Step 6

Place four mushrooms, cup-side up, on plates. Top with fetta, eggplant, tomato, avocado, spinach, pesto and remaining mushrooms, cup-side down. Season. Top burger with sesame seeds, if you like.

Step 7

Blend or process rocket, basil, walnuts, garlic and parmesan until combined. Add oil in a thin steady stream, blend until smooth. Add juice; blend until just combined. If pesto is too thick, add 1 tablespoon water. Season. (Makes 1 cup)