Preheat oven to 350 degrees F.
In a medium mixing bowl, combine the following ingredients: flour, baking powder and salt. Whisk to blend.
Beat the butter and sugar with a hand or stand mixer until light and fluffy.
Add the egg yolks and vanilla to the butter and guar and continue to mix until well blended.
Add half of the flour mixture and beat until smooth.
Add the rest of the flour mixture and beat just until the dough forms into moist clumps.
Use your hands to form the dough into a large ball.
Pinch off the dough and form 1 inch balls.
Use your thumb to press a depression into the center of each dough ball. (You could also use the back of a floured 1/2 teaspoon measuring spoon instead of your thumb.)
Place the dough balls onto a lightly greased baking sheet about 1 - 1.5 inches apart.
Bake until golden brown, approximately 20 minutes.
Allow the cookies to cool for 5-10 minutes on the baking sheet and then transfer them to a wire cooking rack. Allow the cookies to cool completely.