Preheat oven to 325 degrees. Line baking sheets with parchment paper.
In medium bowl, sift together flour blend, cocoa powder, baking powder and salt. Set aside.
To melt chocolate chips, place into small bowl and microwave 30 seconds. Stir and microwave an additional 15 seconds. Stir until smooth.
In large mixing bowl, mix melted chocolate, together sugar, brown sugar, applesauce, non-dairy milk, oil, maple syrup and vanilla. Add flour mixture and stir until dough is well combined.
Place dough into piping bag with large round tip or ziplock bag with 1/2-inch wide cut tip. On prepared cookie sheet, pipe dough into lowercase v-shape {easy way to make a heart-shape}. You can also pipe into circles. Cookies will spread.
Bake cookies 15-17 minutes. Cookies will be soft to the touch. Allow to cool on pan 5 minutes. Place on cooling rack to cool completely.
To make filling, cream shortening until soft, about 1 minute. Add powdered sugar, non-dairy milk and vanilla. Whip until light and fluffy.
Assemble cookie sandwiches by piping filling onto underside of one cookie and topping with another. Repeat with remaining cookies.
Recipe by Sarah Bakes Gluten Free at https://www.sarahbakesgfree.com/2017/02/gluten-free-vegan-whoopie-pies.html