For the macaron shells (recipe adapted from Tessa Huff):

• 1–1/4 cups plus 1-1/2 tablespoons (158 gm) almond flour
• 1–1/4 cups (158 gm) powdered sugar
• 105 gm egg whites (from 3 or 4 eggs)
• ½ cup plus 1-1/2 tablespoons (117 gm) granulated sugar

For the filling:

• ½ cup unsalted butter, at room temperature
• 1–1/2 cups powdered sugar
• ¼ teaspoon salt
• 1 teaspoon vanilla extract
• 1 teaspoon water

Instructions

To prepare the macarons:

1. Line two baking sheets with parchment paper templates. If desired, stencil in pencil on the back of the parchment sheets 4 (4-5”) round circles. Set aside
2. In a food processor, combine the almond flour and confectioner’s sugar and process the mixture for 1-2 minutes, stopping once to scrape down the bowl, until the almond flour is finely ground. Sift the mixture through a fine-mesh sieve into a large bowl. Discard any large chunks left in the sieve or grind again until fine.
3. In the bowl of a stand mixer fitter with a whisk attachment (make sure both are clean and grease-free!), whisk the egg whites on low speed until they begin to foam, form small tight bubbles, and turn opaque. Over the course of a couple of minutes, very gradually increase the speed to medium while slowly adding the granulated sugar. Mix on medium-high until stiff peaks form.
4. Using a flexible rubber spatula, scrape the meringue off the whisk attachment into the bowl with the almond mixture. Begin folding the meringue and almond mixture together, five to ten folds. Scrape in the meringue from the mixer bowl and continue to fold the mixture until incorporated, rotating the bowl as your go. Every so often, gently deflate the meringue by smearing the batter around the side of the bowl. Stop folding once the correct consistency is achieved: the batter should flow very slowly like lava.
5. Fill the prepared piping bag with the macaron batter. Holding the bag straight down, pipe the macarons on the parchment sheet, forming four 4-5” circles  on one sheet. Space them out so they do not bleed into one another. Once one baking sheet is full, tap the bottom of the sheet a few times in each corner with the palm of your hang. Set aside. Pipe any remaining batter onto the second sheet. I made mini macarons by piping ¾” circles onto the prepared baking pan. Set the piped macaron shells aside to rest for 20 to 40 minutes, until a skin forms over the shells and the tops feel dry to the touch.
6. Preheat the oven to 300 degrees with a rack in the center position.
7. Bake the large macaron shells once sheet at a time for 22-25 minutes, until the tops feel secured to the feet but wiggle very slightly when nudged.
8. Remove the baking sheet from the oven and place it on a wire rack. Let the macaron shells cool on the baking sheets for at least 5 minutes. Bake mini macarons in the preheated oven for approximately 7-8 minutes. Allow to cool completely prior to filling.
9. To make the filling, combine all of the ingredients in a medium-sized bowl and beat with a heat mixer until smooth and fluffed. Pipe or spread the frosting onto the large macarons layers, stacking each and finishing the cake with extra frosting and any extra mini macarons, as desired. Allow to chill covered in the fridge for a few hours prior to serving.