Sift together almond meal, cinnamon, powdered sugar and salt over a large bowl.
In a stand mixer, beat egg whites on medium-high until white and foamy, 1-2 minutes. Gradually add granulated sugar, a spoonful at a time, while continuing to beat. Add vanilla extract and beat until stiff, shiny peaks, about 5 minutes.
Fold egg whites into dry mix with a rubber spatula until combined. Continue folding until batter falls in a continuous ribbon off the spatula and reincorporates into the mix on its own. It should not fall of too easily, but should slowly stream off, as if thick honey.
Transfer into batter piping bag with 1/2” tip and pipe 1”-1 1/2” circles onto a sheet lined with parchment or a silicone mat. Whack sheet on hard surface a few times to release air bubbles. Let dry for 30 minutes-1 hour until tops of shells are dry and have formed a “skin”
Preheat oven to 350 and bake 1 sheet at a time for 12 minutes, rotating halfway through. Let cool completely on sheet before removing. Prepare buttercream while cooling.
Combine butter, maple syrup, powdered sugar, salt and vanilla in a stand mixer on low until fully incorporated. Increase speed to high and beat until mixture is light and fluffy, about 5 minutes.
Once shells are cooled. Pipe or spread buttercream onto one cookie and sandwich with another. Store in airtight container at room temperature.
Almond meal and almond flour are interchangeable. You can use either one!
None of that fake stuff! For a truly incredible buttercream, splurge for the higher grade syrup. Trust me, it’s worth it.
You can make this recipe with a hand mixer as well; however, you need a whisk attachment to get the correct meringue texture. I used this mixer with this whisk attachment.