Cut butter into ½- to ¾-inch cubes. Freeze until firm, about 10 minutes.
In the bowl of a stand mixer, whisk together flour, sugar, and salt by hand. Add frozen butter; using the paddle attachment, beat at low speed until butter is broken into small pieces, 2 to 3 minutes. (If any large pieces of butter remain, squeeze between fingers to break up.)
In a 1-cup liquid-measuring cup, whisk together milk, egg yolks, and vanilla bean paste. With mixer on very low speed, add milk mixture to flour mixture in a slow, steady stream, beating just until moist clumps form. Transfer mixture to a large piece of plastic wrap. Using your hands, bring mixture together to form a cohesive dough. Shape dough into a 7-inch disk, and wrap in plastic wrap. Refrigerate for at least 1 hour or up to overnight.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/frozen-german-chocolate-tart/