How to Make It
Whisk together flour, cornstarch, salt, and five-spice powder in a medium bowl. In a stand mixer fitted with the paddle attachment, beat butter, powdered sugar, and vanilla on medium speed until well blended, 1 to 2 minutes. Add flour mixture; beat at low speed just until combined, 30 to 45 seconds. With mixer running on low speed, add pecans, and beat until combined, about 15 seconds.
Divide dough in half, and place each half on a sheet of plastic wrap. Roll each half into a 7-inch log, using wax paper or plastic wrap to help with the rolling. Wrap dough in plastic wrap, and refrigerate 30 minutes, just long enough for the flour to absorb and meld with the butter.
Preheat oven to 350°F with oven rack in upper third of oven. Line a baking sheet with parchment paper.
Remove one dough log from refrigerator (keep second chilled), and unwrap. Using a thin, sharp knife, cut dough into 1/2-inch slices (you will have around 14 slices). Arrange on prepared baking sheet, leaving around 1 1/2 inches between slices. Bake in preheated oven on upper rack until cookies barely start to brown around edges, about 16 minutes, rotating pans after 8 minutes. Let cookies cool on pan 2 minutes; remove cookies to wire rack, and let cool completely, about 10 minutes.
Repeat step 4 with second dough log, or transfer to freezer for later use.