courtesy of Bon Appetit

Ingredients
* 1 sheet frozen puff pastry (half of 17.3-ounce package), thawed * 2 tablespoons butter * 3 large leeks (white and pale green parts only), coarsely chopped * 1 teaspoon dried thyme * 1/2 bunch Swiss chard, ribs removed, leaves chopped (about 2 1/2 cups) * 1 1/4 cups whipping cream * 3 large eggs * 2 large egg yolks * 1 teaspoon salt * 1/4 teaspoon ground black pepper * Pinch of ground nutmeg

Method

1. Roll out pastry on floured work surface to 12-inch square. Transfer to 9-inch-diameter glass pie dish. Trim overhang to 1 inch. Fold under; crimp edges. Cover; chill. Melt butter in large nonstick skillet over medium-low heat. Add leeks and thyme. Sprinkle with salt and pepper. Cover; cook until leeks are very tender but not brown, stirring often, about 10 minutes. Add chard; saut until wilted, about 2 minutes. Remove from heat; cool. Position rack in bottom third of oven; preheat to 425°F. Whisk cream and next 5 ingredients in large bowl. Mix in cooled leek mixture. Pour filling into crust. Bake tart 15 minutes. Reduce heat to 350°F and bake until filling is puffed and just set in center, about 15 minutes longer. Transfer to rack; cool 10 minutes.