Preheat oven to 425 degrees F. Unfold pastry sheet; cut along fold line to make 3 strips, trimming rough edges. Cut each strip in half crosswise. Place pastry rectangles on an ungreased baking sheet and bake until golden brown, 12 to 14 minutes. Transfer pastry to a rack and cool (about 8 to 10 minutes), then cut horizontally into 2 layers.
While pastry bakes, in a medium bowl whisk the goat cheese, 6 tablespoons powdered sugar, vanilla, and salt until blended. Using electric mixer, beat whipping cream in another medium bowl until peaks form; fold into cheese mixture. Chill 10 to 15 minutes.
Heat the jam in a medium microwave-safe bowl until just melted (about 10 seconds). Add berries. Toss to coat.
Just before serving, put bottom halves of pastry on plates; top with mousse and raspberries. Sprinkle with minced thyme, cover with top half of pastry, and dust with powdered sugar. Garnish with thyme sprigs.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.