In the container of a food processor, add walnuts and sugar; pulse until ground. Add flour and pulse until just incorporated. Add butter and pulse until pea-size crumbs form. Add egg yolk and pulse just until dough comes together, 5 to 10 seconds.
On a lightly floured piece of parchment paper, roll crust out to a ⅛-inch-thick, 11-inch round. Transfer to a 9½-inch tart dish, pressing into bottom and up sides (if dough cracks, gently press together). Freeze for 15 minutes.
Top with a piece of parchment paper, letting ends extend over edges of dish. Add pie weights. Bake for 15 minutes. Carefully remove paper and weights. Bake until crust is golden brown, 15 minutes more. Let cool on a wire rack for 15 minutes.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/bourbon-caramel-chocolate-tart/