01 - Cream butter and powdered sugar in a large bowl until smooth and fluffy. Beat in vanilla extract until fully incorporated.
02 - Sift flour and salt into the butter mixture. Mix until just combined and a cohesive dough forms.
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 - Preheat oven to 350°F and line baking sheets with parchment paper.
05 - Slice chilled dough into 1/2-inch thick rounds. Place cookies on prepared baking sheets, spacing 1 inch apart.
06 - Bake for 12-14 minutes until edges are just turning golden. Transfer to wire rack and cool completely.
07 - Whisk egg yolks, 1/4 cup granulated sugar, heavy cream, and vanilla in a small saucepan. Cook over medium-low heat, stirring constantly, until slightly thickened, approximately 4-5 minutes. Remove from heat and cool completely.
08 - Spoon a small amount of cooled custard onto the center of each cookie. Gently spread to create an even layer.
09 - Sprinkle a thin layer of granulated sugar over the custard on each cookie. Use a kitchen torch to caramelize sugar until golden and crisp. Let set for 5 minutes before serving.