Preheat oven to 325 F. Line two baking sheets with parchment paper. 

In a stand mixer with the paddle attachment (or using a hand mixer) cream the butter, shortening, and brown sugar until well mixed, about 2-3 minutes. Add egg yolks, vanilla extract, and almond extract and mix well until incorporated. Add flour and salt. On low speed, mix until no more dry flour remains. Be careful not to overmix. 

Roll dough into small balls (about a heaping half tablespoon and 1 inch big). Lightly whisk the egg whites to help break up the proteins. Dip dough balls into egg whites then into pecans to coat evenly. Evenly arrange the cookies on the cookie sheets, about 16-20 cookies per sheet. (I bake one sheet at a time and rotate sheets.) Make an indent in the middle of each cookie with your thumb.

Bake for 15-18 minutes or until the edges of the cookie are very lightly browned. If some of the cookies have lost their indent because of the baking, you can press it back down with a half teaspoon measuring spoon while the cookies are still warm. 

Allow cookies to completely cool on a cooling rack, then fill with about 1/2 teaspoon of your favorite jam. Enjoy!