Preheat oven to 375°F/190°C/Gas Mark 5.
Toss bread with a tablespoon of olive oil, a pinch of salt and pepper. Spread out in a single layer on baking sheet and bake until golden brown and crunchy, about 12 - 15 minutes.
Stack Swiss chard leaves on top of each other and roll up tightly. (like a cigar) With a sharp knife, thinly slice into ribbons and set aside.
Heat a large saute pan over medium heat - add 1 tablespoon olive oil. Add red onion, garlic and chard stems (not leaves).
Cook for 6 - 8 minutes, until softened, but still have some texture. Add Granny Smith apple and cook an additional 2 minutes. Remove from heat and set aside.
Add Swiss chard leaves to the onion mixture in the pan and stir to combine. (The warmth of the vegetables will help to wilt the ribbons of chard)
Add remaining ingredients to a large mixing bowl. Add onion mixture and toasted bread to the bowl and toss to combine.
Whisk ingredients for dressing together and pour over bread mixture. Toss to thoroughly combine and serve.