To make the marinated mushrooms, put the mushrooms into a small bowl, add the balsamic vinegar, honey, salt and freshly ground black pepper. Stir well and leave to infuse for 10 minutes. Drain off the excess marinade and set aside.
Preheat the grill to its highest setting.
Heat the olive oil in a large pan, add the spinach, lemon juice, salt and freshly ground black pepper, and toss well. Cook for 1-2 minutes until wilted.
Remove from the heat, drain and squeeze out excess juice. Put the spinach into a chefs' ring on a baking tray and put the drained mushrooms on top. Remove the chefs' ring, add the sliced goats' cheese and place under the grill for four minutes or until slightly browned.
To make the 'pesto', put all the ingredients in a pestle and mortar or mini blender and grind or blend until you have a smooth paste.
To serve, slide the mushroom stack onto a small plate and drizzle the pesto round the side.