01 - Beat unsalted butter and powdered sugar in a large bowl until smooth and fluffy. Incorporate vanilla extract until fully combined.
02 - Sift flour and salt into the 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.
04 - Heat oven to 350°F. Line baking sheets with parchment paper.
05 - Cut chilled dough logs into 1/2-inch thick rounds. Arrange on prepared baking sheets and bake 12 to 14 minutes until edges turn light golden.
06 - Whisk egg yolks, granulated sugar, heavy cream, and vanilla in small saucepan. Cook over medium-low heat, stirring constantly, 4 to 5 minutes until slightly thickened. Remove from heat and cool completely.
07 - Spread cooled custard onto center of each cooled cookie. Sprinkle thin layer of granulated sugar over custard. Torch sugar until golden and crisp. Let set 5 minutes before serving.