Preheat oven to 350 degrees F (175 degrees C).

In a large bowl, beat butter, shortening, brown sugar, eggs, and vanilla until fluffy.

In a separate bowl, whisk together flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until well combined.

Stir in the salted peanuts.

Drop by rounded teaspoons onto a greased cookie sheet.

Flatten each cookie with the bottom of a greased glass dipped in sugar.

Bake for 10 minutes, or until golden brown around the edges.

Let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.