Line an 8x8-inch baking pan with baking parchment, leaving some to overhang the edges.

In a small bowl, whisk together flour and salt.

In a stand mixer fitted with the paddle attachment, beat butter on medium-low until smooth and creamy. Add sugar, and beat on medium-low until light and fluffy, about 2 minutes.

Add vanilla, and mix on low. Scrape down bowl.

Add flour mixture in two additions, mixing on low until just combined between additions.

Mix in pecans.

Press dough into prepared pan. Score lightly into 2x2-inch squares. Refrigerate at least 30 minutes.

Preheat oven to 300°F.

Bake 50 to 60 minutes, or until golden brown around the edges.

Cool in the pan, before lifting out by the parchment and cutting along the score marks.