In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar with a mixer at medium speed until creamy, 3 to 4 minutes, stopping to scrape sides of bowl. Add egg, beating well.
In a medium bowl, sift together flour and baking powder. Add flour mixture, almonds, and salt to butter mixture, beating until well combined. (This is a very wet dough.)
On a work surface, place a large sheet of parchment paper. Place dough in middle of parchment; top with a second sheet of parchment. Roll dough into a 16x6-inch rectangle. Freeze until firm, about 15 minutes.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/red-wine-poached-pear-tart/