Free-form creations like this simple Swiss chard galette have an appealing rustic look and taste that match the tone of the season.
Slice chard stems into 1/4-inch pieces. In a large skillet, heat 1 tablespoon oil over medium heat. Add the stems and onion, and cook, stirring, until slightly brown, 8 to 10 minutes.
Cover skillet, and reduce heat to low. Cook, stirring occasionally, until stems are very soft, about 15 minutes. Add the vinegar, and cook, stirring, until liquid is reduced by half, about 2 minutes. Season with salt and pepper. Remove from heat, transfer onion mixture to a nonreactive bowl; set aside.
Heat remaining tablespoon oil in same skillet over medium-high. Add anchovies, if using; saute, stirring frequently, 1 minute. Add chard leaves, and saute until slightly wilted, about 1 minute. Stir in thyme; season with salt and pepper, and set aside.
In the bowl of an electric mixer fitted with the paddle attachment, combine the goat cheese and 2 tablespoons cream. Beat mixture until smooth, about 1 minute. Stir in the n utmeg; season with salt and pepper, and set aside.
Preheat oven to 375 degrees. On a large piece of parchment paper, roll out dough to a 1/4-inch-thick round, about 12 inches in diameter. Arrange onion mixture evenly over the dough, leaving a 3-inch border around edge. Spread goat-cheese mixture over onion mixture, and top with the chard mixture. Sprinkle with pine nuts and golden raisins. Fold edges of dough over, and press down gently to seal. Transfer tart, on parchment paper, to a baking sheet, and refrigerate 15 minutes.
In a small bowl, beat egg yolk with remaining tablespoon cream. Brush exposed dough with egg wash, and bake until crust is golden, 40 to 45 minutes. Serve warm or at room temperature.