01 - Cream butter and powdered sugar in large bowl until smooth and fluffy. Beat in vanilla extract until incorporated.
02 - Sift flour and salt into butter mixture. Mix until just combined and dough forms without overworking.
03 - Divide dough in half and shape into 2-inch diameter logs. Wrap tightly in plastic wrap and refrigerate for minimum 30 minutes until firm.
04 - Preheat oven to 350°F and line baking sheets with parchment paper.
05 - Slice chilled dough into 1/2-inch thick rounds. Place on prepared baking sheets and bake 12-14 minutes until edges are just golden. Cool completely on wire racks.
06 - Whisk together egg yolks, granulated sugar, heavy cream, and vanilla in small saucepan. Cook over medium-low heat, stirring constantly, until mixture thickens slightly, about 4-5 minutes. Remove from heat and let cool completely.
07 - Spoon small amount of cooled custard onto center of each cookie. Smooth gently with back of spoon or offset spatula.
08 - Sprinkle thin layer of granulated sugar over custard-topped cookies. Use kitchen torch to caramelize sugar until golden and crispy. Let set 5 minutes before serving.