Preheat your oven to 300 degrees. Get out two baking sheets and cover them with parchment paper. I make a circle template for myself and flipped the parchment paper over so the ink wouldn't be touching my batter.
I couldn't find almond flour so I made my own. I placed 1 and ½ cups of almonds in my food processor. I turn it on high until everything was somewhat fine. I sifted the almonds and placed the coarse almonds back into the food processor and repeated the process. Once I got enough almond flour, I placed what I had sifted back into the food processor on high for another 3 minutes. I sifted it once more and discarded any coarse pieces.
In a mixing bowl, place your egg whites in. With the whisk attachment on high speed, whip until the white are at a soft peak. It would only take 2-3 minutes.
At this point, with the mixer still going, slowly add in the granulated sugar. Keep mixing until the egg whites come to a stiff peak. Turn the mixer off.
In a separate bowl, sift the powdered sugar, almond flour and salt. Whisk the dry ingredients together.
Add in the lemon zest to the dry ingredients and whisk it.
Slowly add a small portion of the dry ingredients into the stiff meringue. Fold it in with your whisk until it is incorporated. Continue to add in small portions. I would do thirds. If you over-mix the batter, the macarons will come out somewhat flat. Like mine. If you under-whisk them they come very fluffy.
Once you have all the batter combined, it should be thick. It will still have a little movement though.
Add the batter into a piping bag with a round tip. Pipe your circles of batter.
After you piped all your macarons, let them sit for 1 hour or until the tops are no longer sticky.
Place them in the oven for 15 minutes.
Remove them from the oven and let them cool.
Once they have cooled, unstick them from the parchment paper and match your shells so the tops and bottoms are the same size.
Mixed Berry Buttercream
In a saucepan, add in the raspberries, blackberries, and granulated sugar. Turn heat on medium and mash the berries to get the juice flowing.
It will take 10-15 minutes for the berries to release all the juice.
Strain the berries and discard the skins and seeds. I reallly love blackberries and really hate the seeds.
Let the mixed berry juice cool to room temperature.
Place the butter in the stand mixer and turn on medium. Use the paddle attachment. Once the butter looks light and airy, add in the powdered sugar. I normally add 1 cup at a time and keep the mixer on low.
Once all the powdered sugar is incorporated, turn the mixer on high and let it whip for 3-5 minutes. The buttercream will be light and fluffy.
Optional - at this time, I took out ¼ of the buttercream for my lemon buttercream.
I added about a ¼ cup of mixed berry juice into the remaining buttercream and let it mix on low until combined. I bumped the speed up to high and let it whip another minute or two.
I squeezed half a lemon into the other buttercream and mixed it up.
Assembling
Put the buttercream in a piping bag and pipe the filling on one half of your macaron.
Carefully place the top on without applying too much pressure. Otherwise, your top will break.
Notes
Macaron recipe was adapted from Nerdy NummiesMake sure your egg whites are at room temperature.*If you choose to not make lemon buttercream, I would add ⅓ cup of mixed berry juice instead of ¼ cup.