How to Make It
Preheat the oven to 400°. Arrange the baguette slices on a baking sheet and brush lightly on both sides with 3 tablespoons of the olive oil. Bake for about 8 minutes, or until lightly browned.
Heat 2 tablespoons of the olive oil in a large skillet. Add the onion and garlic and cook over low heat, stirring, until the onion softens, about 5 minutes. Add the beans and cook, stirring, until heated through, about 3 minutes. Scrape the mixture into a food processor or blender and puree until smooth. With the machine on, add 2 tablespoons of the olive oil. Transfer to a bowl, stir in the thyme and season with salt and pepper; keep warm.
Wipe out the skillet and set it over moderately high heat. Add the Swiss chard and stir until wilted. Transfer to a colander and let cool slightly, then squeeze out the excess liquid.
Heat the remaining 1 tablespoon of olive oil in the skillet. Add the Swiss chard and season with salt and pepper. Cook over moderately high heat, stirring, until heated through.
Spread each toast with about 1 tablespoon of the warm bean puree and top with some of the Swiss chard. Drizzle lightly with some of the truffle oil and serve warm or at room temperature.