Place all of the ingredients for the pesto in a food processor and blitz until combined. Taste and correct seasoning.
The Chicken Burgers will taste best cooked over hot coals, so get the braai going. Brush each Chicken Burger with a little oil and braai until golden brown. Braai the mushrooms and pineapple slices until just cooked and the edges are charred.
Top a mushroom (underside up) with baby spinach and a slice of tomato. Add a Chicken Burger, a slice of cheese, pineapple, a second Chicken Burger patty and a second slice of cheese. Top with pesto and cover with a second mushroom. Season with cracked salt and pepper, as you assemble.
Serving Size 4