Preheat oven to 350F. In a large mixing bowl, combine the coconut butter or margarine with almond butter, using an electric mixer, until smooth.
Add the brown sugar and beat until light and fluffy.
Add the egg and vanilla and beat until combined.
Slowly add the package of sugar cookie mix, baking powder, and salt. Mix until combined.
Roll the dough into tablespoon size balls. Roll the balls in the sugar and place on a parchment paper or silicone pad lined baking sheet.
Place the cookies several inches apart, as they will spread. Press an indentation with your thumb in the center of each cookie.
Heat the plum jam in a small saucepan for 2 minutes, stirring until soft and melted. Spoon 1 teaspoon of the jam into the center of each cookie. Bake for 15 minutes, cool completely before transferring to a plate.