Preheat the oven to 350. Line two baking sheets with parchment paper.
In a large bowl, mix the applesauce, almond butter, date sugar, espresso powder, and vanilla extract. Add the flaxseeds, oat flour, baking soda, and salt and mix until combined.
Scoop into tablespoon-sized balls and line on the prepared baking sheet. Flatten – the cookies won’t spread during baking. Bake for 14-16 minutes, until the cookies are slightly brown around the edges. Let the cookies cool completely.
While the cookies cool, make the chocolate filling. Add the sweet potato, cocoa powder, date syrup, espresso powder, and vanilla extract to a food processor. Blend until smooth, adding the non-dairy milk if the mixture is very thick.
When the cookies are completely cool, pipe or spread the chocolate filling on the bottom of a cookie. Press a second cookie on top to create a sandwich. Repeat with the remaining cookies. If the frosting starts to get too soft, place the cookie sandwiches in the freezer while piping. Serve and enjoy!