01 - Cream together the butter and powdered sugar in a large bowl until smooth and fluffy. Beat in vanilla extract until fully incorporated.
02 - Sift the flour and salt into the butter mixture. Mix until just combined and a soft dough forms, being careful not to overwork.
03 - Divide the 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 until firm.
04 - Preheat oven to 350°F and line baking sheets with parchment paper.
05 - Slice the chilled dough logs into 1/2-inch thick rounds and arrange on prepared baking sheets. Bake for 12 to 14 minutes until edges are just beginning to turn golden. Allow cookies to cool completely on the pans.
06 - While cookies bake, whisk together egg yolks, 1/4 cup granulated sugar, heavy cream, and vanilla in a small saucepan. Cook over medium-low heat, stirring constantly, for 4 to 5 minutes until mixture thickens slightly. Remove from heat and let cool completely.
07 - Spoon a small amount of cooled custard onto the center of each cookie and smooth gently. Sprinkle a thin, even layer of granulated sugar over the custard. Using a kitchen torch, caramelize the sugar until golden and crisp. Let set for 5 minutes before serving.