Directions:

Make simple syrup: In a small pot, combine ½ cup water and ½ cup sugar and bring to a boil, stirring until sugar dissolves. Let cool.

Preheat oven to 350 degrees. Separate 4 eggs. Split 1 vanilla bean and scrape seeds into a bowl. Add ¼ cup sugar and egg whites. Whip to soft peaks. In another bowl, beat yolks lightly. Fold yolks into whites.

Lightly coat an 18-by-12-inch silicone baking mat with cooking spray and place on a baking tray. Spread egg mixture evenly over mat. Sprinkle ½ cup chopped Sicilian pistachios over batter. Bake until spongy, 6-8 minutes. (Do not let edges brown.)

Let omelet cool slightly before loosening edges and flipping over onto a piece of lightly greased parchment paper. Cut into eight even-size squares and brush lightly with simple syrup. Layer squares on top of one another, pressing down lightly after adding each layer. Chill at least 1 hour before slicing and serving.