01 - Cream together butter and powdered sugar in a large bowl until smooth and fluffy. Beat in vanilla extract.
02 - Sift flour and salt into the butter mixture. Mix until just combined and a dough forms.
03 - Divide dough in half and shape into logs about 2 inches in diameter. Wrap in plastic 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 and place on prepared sheets. Bake for 12 to 14 minutes until edges just begin to turn golden. Cool completely.
06 - Whisk egg yolks, sugar, heavy cream, and vanilla in a small saucepan. Cook over medium-low heat, stirring constantly, until slightly thickened, about 4 to 5 minutes. Remove from heat and cool completely.
07 - Spoon a small amount of cooled custard onto the center of each cookie. Sprinkle a thin layer of granulated sugar over the custard and use a kitchen torch to caramelize until golden and crisp. Let set for 5 minutes before serving.