In bowl of electric mixer fitted with paddle attachment, mix butter and sugar until just incorporated. Add egg and almond extract. Mix again on low until combined.
In medium bowl, whisk together flour, almond flour and salt. Add flour mixture to butter mixture. Mix on low until dough forms. Roll dough flat between two sheets of parchment paper to about 1/4-inch thickness and chill until ready for use, at least 30 minutes.
Preheat oven to 350°F. Line two baking sheets with parchment paper.
Cut dough into stocking shapes using 3-inch cookie cutter, place each shape on prepared pan.
Bake 7-10 minutes, or until cookies are lightly golden around edges. Transfer cookies to a wire cooling rack to cool completely.
Using a small artists’ brush, paint corn syrup or piping gel on sock portion of stocking (avoid the cuff). Dip cookie in rainbow nonpareils. Let dry 10 minutes. Repeat with remaining cookies.
Use same brush to paint corn syrup onto cuff portion of stocking. Dip in white nonpareils; let dry 10 minutes. Brush over white nonpareils on cuff portion again with more corn syrup and dip a second time. Let stand until completely dry, about 1 hour.