In a large skillet, heat 2 tablespoons of the olive oil over moderate heat. Add the onion and garlic and cook, stirring, until the onion is translucent, 6 to 7 minutes. Add the Swiss chard, season with salt and pepper, and cook, stirring, for 5 to 7 minutes. Remove the pan from the heat and discard the garlic. Stir in the almonds, mint leaves and raisins. Season with salt and pepper, if needed. Let the stuffing cool to room temperature.