01 - In a large bowl, beat unsalted butter and powdered sugar until light and fluffy. Add vanilla extract and mix until incorporated.
02 - Sift flour and salt into the butter mixture. Mix gently until just combined and a cohesive dough forms.
03 - Divide dough in half and shape each portion into logs approximately 2 inches in diameter. Wrap tightly in plastic wrap and refrigerate for at least 30 minutes.
04 - Preheat oven to 350°F. Line baking sheets with parchment paper.
05 - Cut chilled dough logs into 1/2-inch thick rounds. Place slices on prepared baking sheets with slight spacing between each cookie.
06 - Bake for 12 to 14 minutes until edges begin to turn golden. Transfer to a cooling rack and let cool completely.
07 - In a small saucepan, whisk together egg yolks, granulated sugar, heavy cream, and vanilla. Cook over medium-low heat, stirring continuously, until mixture thickens slightly, about 4 to 5 minutes. Remove from heat and allow to cool.
08 - Spoon a small portion of cooled custard onto the center of each cookie. Gently spread to create an even layer.
09 - Sprinkle a thin, even layer of granulated sugar over the custard on each cookie. Using a kitchen torch, caramelize the sugar until golden and crisp. Allow to set for 5 minutes before serving.