1Whisk together the dry ingredients (black cocoa powder, flour, baking soda, salt).
2Cream the butter and sugar until fluffy in a stand mixer with paddle attachment. Mix half dry ingredients in with butter/sugar until just combined. Repeat with other half of dry ingredients. Transfer the dough onto plastic wrap and press into a flat disk. Wrap the disk and refrigerate for 1 hour.
3Roll the dough between two pieces of plastic wrap or parchment paper to a thickness of 1/8 inch. Cut out with a large round cookie cutter or another shape of your choosing. Transfer the cutouts to a parchment lined baking sheet. Bake at 325 degrees for 15 minutes (9-11 minutes for smaller cookies).
4Cool the cookies completely while preparing the buttercream.
1Cream the butter in stand mixer with paddle attachment. Mix powdered sugar into butter, 1 cup at a time. Add the vanilla bean paste and milk, beat 3-4 minutes.
2Transfer into a pastry bag fitted with a star tip, or to a Ziploc bag (snip off a corner), or just frost with a spatula. Pipe frosting onto half of the cookies, then top with the remaining cookies. Enjoy!