Cream butter and sugar on low in a mixer with a paddle attachment.
Add egg, mix briefly, then add dry ingredients and nuts; mix until combined.
Shape dough into a flat disk; chill for 30 minutes if too sticky.
Roll out dough on a floured surface to a 12-inch circle.
Transfer dough to a 9.5-inch tart pan, pressing into edges; trim excess.
Freeze tart shell for 30-60 minutes.
Preheat oven to 350°F, line tart with parchment and pie weights.
Bake for 24-28 minutes, removing weights for the last 5 minutes; cool crust completely.