Beat butter, shortening, and sugar on medium speed until light and fluffy. Scrape the bowl. Add pandan paste and beat until combined. Beat in as much of the flour as you can with the mixer. Stir in remaining flour. Knead slightly to form a ball.
If you are using cookie pan, press dough into pan cavities, filling two thirds full. Bake in 350°F oven for 8 to 9 minutes. Cool in pan for 10 minutes. Remove and allow cookies to cool completely on a wire rack. Decorate as desired.
If you are using cookie cutters, wrap dough in cling wrap and chill in the fridge for 30 minutes. Remove and roll out to ¼ inch thick on a lightly floured surface. Cut into desired shape and place on cookie sheet 1 inch apart. Bake in 350°F (180°C) oven for 8 to 9 minutes. Allow to cool on cookie sheet for 10 minutes. Remove and allow cookies to cool completely on a wire rack. Decorate as desired.