Heat the oil in a frypan over medium heat, and fry the onion until it's softened but not colored. Add the cubed bread and cook, stirring often, until it’s crisped and beginning to turn golden. Remove the pan from heat and add the chopped Swiss chard or spinach, cranberries and pecans. Give it all a stir and let the chard soften slightly from the heat of the pan. Pour in the stock, then add salt, pepper and thyme leaves. Mix well until the bread is breaking down and soft from the stock. Chill until completely cold, about 1 hour.
2 Tbsp olive oil, 4 slices stale white bread, 1 medium brown onion, 4 leaves Swiss chard, 1/2 cup dried cranberries, 1/2 cup pecans, 2/3 cup chicken stock, 1 1/2 tsp flaky salt, 1 tsp ground black pepper, 4 sprigs thyme