Set the temperature of the oven to 350 F (175 C). Cover the baking sheet with silicone mats or parchment paper.
In a bowl, mix softened butter with the granulated sugar until light and fluffy.
Add mashed purple yam or ube jam to the butter-sugar mixture and mix until thoroughly combined.
Then, beat in the egg and vanilla extract until smooth.
In another bowl, mix salt, flour and baking powder.
Slowly add the dry ingredients to the wet ingredients and mix until it forms a dough. Add nuts or white chocolate chips and evenly distribute them.
Put the dough balls onto the baking sheet, spacing them around 2 inches apart. You can use a spoon or cookie scoop for this.
Gently press down each cookie using your finger or a spoon.
Put them in the preheated oven and bake until the edges are golden brown, it may take around 10-12 minutes.
Let the cookies cool on the baking sheets for few minutes before transferring them to the wire racks to cool completely.
After it gets cooled, you can enjoy the ube cookie with a glass of milk or any beverage of your choice.