Preheat your oven to 350 degrees Fahrenheit.

In a small bowl, whisk together the oat flour, erythritol, cocoa powder, baking powder, and salt.

In a stand mixer bowl with beater attachment, add the coconut oil, almond milk, vanilla extract, and stevia extract.  Mix on low speed until completely mixed.

Dump the dry ingredients into the stand mixer and mix until completely mixed.  Cover the bowl and refrigerate for 30 minutes.

Roll ⅓ of the dough in between two silicone baking sheets until ~⅛" thick.  Use a 2" circle cookie cutter to punch circles into the dough.  Peel away the dough surrounding the circle shapes, putting the dough back into the stand mixer bowl, and transfer the silicone sheet with the circles onto a cookie tray.

Bake for 12 minutes.  Carefully transfer the silicone sheet onto your counter or a wire cooling rack to cool completely.  Keep re-rolling the dough and baking until all the dough is used up.

In a large bowl, whisk together the erythritol, water, and vanilla paste, until you get a frosting-like texture.

Scoop the frosting onto half of the wafer cookies, then gently press the remaining wafer cookies on top to make sandwich cookies.  Serve and enjoy!