– Butter – Shortening – Salt – Egg – Brown Sugar – Flour
In a large bowl, cream together butter, shortening, brown sugar, and salt until light and fluffy, about 5 minutes. Beat in egg yolk and vanilla until well incorporated.
Gradually beat the flour into creamed mixture. Refrigerate cookie dough, covered, until easy to handle, at least 30 minutes.
Preheat oven to 350°. In a shallow bowl, whisk egg white until foamy. Place pecans on a plate or in a shallow bowl. Using a #60 cookie scoop, shape dough into balls. Dip balls in the egg white then roll in pecans.
Place balls 2 in. apart on ungreased baking sheets. Press an indentation in the center of each with the back of a teaspoon, being careful not to make the bottom too thin or create a hole.
Bake until edges are light brown, 10 – 12 minutes. Remove pans from the oven and let cool for 3 minutes on the pan and then transfer from pans to wire racks. Cool completely before filling.