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 at least 30 minutes.
04 - Heat oven to 350°F and line baking sheets with parchment paper.
05 - Cut chilled dough logs into 1/2-inch thick rounds. Arrange on prepared baking sheets and bake for 12 to 14 minutes until edges turn golden.
06 - Whisk egg yolks, granulated sugar, heavy cream, and vanilla in a small saucepan. Cook over medium-low heat, stirring constantly, until mixture thickens slightly, about 4 to 5 minutes. Remove from heat and let cool completely.
07 - Spread a small amount of cooled custard onto each cookie center. Sprinkle thin layer of granulated sugar over custard and torch until sugar forms a golden, crisp caramelized layer. Let set 5 minutes before serving.