Place the softened butter, sugar, vanilla, and orange zest in a large bowl (or the bowl of a stand mixer). With a hand mixer (or stand mixer with a paddle attachment) on medium speed, beat until light and fluffy, 2-3 minutes. Add the cinnamon and flour and mix on low speed, just until combined. Add the pecans and mix on low just until combined, scraping the bottom and sides of the bowl as needed. Preheat the oven to 325 F. Position one oven rack in the top one-third of the oven, and the other rack in the bottom one-third position. Shape slightly mounded tablespoonfuls of dough into oval shape logs, about 2 ½ -inches long. Place them on two baking sheets, about 2-inches apart and curve them into half-circles. Bake for 20-22 minutes, rotating the baking sheets from upper to lower rack half-way through, just until the bottoms of the cookies are lightly golden. Let cool on the sheet tray for 10 minutes before transferring to a bowl of powdered sugar. Dredge them while they are warm, then transfer to a cooling rack set over a sheet tray to cool completely. Once cool, sprinkle with additional powdered sugar, if desired. Store in an air-tight container in a single layer, between layers of parchment paper, at room temperature for up to 1 week.