Preheat the oven to 400°F. Line baking sheets with parchment paper.: The moment you slide the first tray in you'll smell a warm, slightly toasty note of chocolate once the dough starts to bake, signaling the Maillard reactions taking off. Proper preheating ensures even rise and predictable bake time, so heat the oven fully before baking. A common mistake is placing cold dough into an oven that is still warming, resulting in over spread or uneven texture. Make sure parchment lies flat on the sheet so cookies bake on a consistent surface, and if your oven runs hot or cool, rotate the pans halfway through to maintain an even color.
In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with an electric mixer, cream together the shortening and sugar until light and fluffy.: You will notice the color lighten and the texture become airy as sugar cuts through the shortening, creating tiny pockets that help the cookie feel light. I listen for a slight change in the mixer’s hum when the mixture is aerated enough. Creaming properly matters because it traps air that helps the cookie rise subtly and keeps the crumb tender. Avoid creaming at too high speed, which can heat the fat and lead to greasy batter, and stop once the mixture is visibly lighter and soft to the touch.
Add in the egg, vanilla, buttermilk, and water and mix until the ingredients are fully incorporated.: After adding these liquids, the batter will loosen and take on a glossy sheen, signifying good emulsification. The buttermilk adds a touch of tang while water adjusts the batter’s texture for the right drop consistency. If the mixture looks curdled, this usually means the butter or shortening was too cold; let the bowl sit briefly or mix a bit slower until it smooths out. Overmixing here can incorporate too much air or activate gluten later, so mix just until smooth.
In a medium bowl, whisk together the flour, baking soda, cocoa, and salt. Slowly add the dry ingredients to the shortening mixture and mix until just combined. Use a rubber spatula to gently fold the chocolate chips into the batter.: As you add the dry mix, the batter will thicken and become matte in appearance, and you should stop mixing as soon as streaks of flour disappear. Folding in the semisweet chocolate chips keeps pockets of melted chocolate rather than breaking them down and creating streaks. This technique preserves texture and creates delightful bites of melted chocolate. A frequent error is overmixing, which produces a dense cookie, so fold gently until evenly distributed.
Use a medium cookie scoop (1.5 tablespoons) to drop batter onto prepared cookie sheets about 2 inches apart.: Scooping ensures uniform cookies so they bake evenly; each mound should have a slightly domed top. Giving them space prevents them from joining as they spread, and if the dough seems too soft to hold shape, chilling the scooped dough briefly tightens the outside and helps it bake into tidy rounds. Avoid scooping with a spoon because sizes will vary and lead to inconsistent bake times.
Bake for 8-9 minutes in the preheated oven.: You'll see the edges set and the centers remain soft, with the tops appearing matte rather than glossy when they are ready to come out. The aroma of cocoa and baked sugar becomes prominent right at the end of this window. Pulling cookies out too early leaves them underbaked and collapse prone, while overbaking dries them; aim for that slight springiness when you touch a top gently with a fingertip. If your oven's temperature is uncertain, check at the lower time and adjust for future batches.
Allow cakes to cool on baking sheets for 5 minutes before removing to wire racks to cool completely.: During this resting time the cookies finish setting, and removing them too soon can cause them to tear or deform. Cooling on a rack ensures air circulates underneath so bottoms do not become soggy. If you skip the rest on the sheet, the cookies may fall apart when transferring; use a thin spatula and patience to lift them without breaking.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium-high speed for 3-4 minutes.: The butter should become pale and airy, with a light, whipped aroma. This aeration builds the structure for a silky buttercream that pipes and spreads well. If the butter is too cold it will not whip properly, and if too warm it will be greasy; aim for room temperature and beat until visibly lighter in color and texture.
Turn the mixer down to low speed and gradually add in the powdered sugar until thoroughly combined. Turn the mixer back up to medium-high speed and mix for 5 minutes.: Adding powdered sugar slowly prevents a dusty cloud and helps the sugar integrate smoothly for a velvety texture. After the full mixing, the buttercream should be light and fluffy, with a sweet, creamy scent. If the frosting feels grainy, you may need to sift the powdered sugar or beat longer. Too much speed at first can fling sugar everywhere, so keep it controlled until the powdered sugar is mostly incorporated.
Add in the cherry juice and vanilla and beat an additional 2 minutes.: The cherry juice brightens the flavor and colors the buttercream slightly, while the vanilla rounds it out. The mixture will take on a fresh, fruity aroma and become softer. If the buttercream thins too much, pause and let it firm in the fridge briefly; if it is too thick, add milk sparingly. A common misstep is adding too much liquid at once; always add one teaspoon at a time and check consistency.
Use a rubber spatula to fold the chopped cherries into the buttercream.: Folding preserves chunks of maraschino cherries so you get bursts of texture and flavor rather than uniformly smooth frosting. The buttercream should show ribbons of fruit, adding visual interest and tiny chewy bits. If the cherries are too wet, pat them dry before folding to avoid thinning the frosting.
Note: If the buttercream is too thick, you can add a little milk in 1 teaspoon at a time until the desired consistency is reached.: If the buttercream is too thick, you can add a little milk in 1 teaspoon at a time until the desired consistency is reached. : When you add a touch of milk , the buttercream transforms, becoming more pipeable and glossy. Add the milk slowly and test frequently to avoid overshooting the consistency. If you add too much, chill the frosting briefly and rewhip to recover some structure.
Spoon or pipe the buttercream onto the flat sides of half the cookies and top with remaining cookies.: The finished assembly should look tidy, with a visible ring of buttercream at the edges if you pipe a generous swirl. Press gently when sandwiching to spread the frosting evenly without squeezing it out. A typical mistake is overfilling which causes the filling to ooze; measure or pipe consistently so each sandwich is uniform.
