Preheat oven to 350°F.

Line 2 large baking sheets with parchment paper.

Put powdered sugar, almond flour, and salt in a food processor pulsing several times. Continue for about 30 seconds or pulse until the ingredients are fine and well combined.

Using a flour sifter, sift the above ingredients into a large bowl. Set aside.

Place the 3 egg whites in the clean bowl of a stand mixer fitted with a whisk attachment. Beat on medium speed until opaque and foamy, about 30 seconds. Now add a pinch of cream of tartar, increase the speed to medium high, continue to beat until the egg whites are white in color and hold the line of the whisk, about 1 minute.

Continue to beat, slowly adding the granulated sugar, and vanilla extract...until the sugar is combined, the peaks are stiff, and the whites are shiny, about 1 minute more. Do not over whip. Transfer the meringue to a large bowl.

Now you will need to spoon half of batter into pastry bag fitted with 1/2-inch plain round tip. Pipe batter onto each prepared sheet in 12 walnut-size mounds, spacing mounds apart because cookies will spread slightly.-

Take a rubber spatula, and now gently fold the dry mixture with the egg whites in four different scoops until the dry ingredients are just combined.

Now you will need to spoon half of batter into pastry bag fitted with 1/2-inch plain round tip. Pipe batter onto each prepared sheet in 12 walnut-size mounds, spacing mounds apart because cookies will spread slightly.

Bake cookies, 1 sheet at a time, until firm to touch in center and dry and cracked on top, about 7 minutes ..... pull the pan out and then rotate and bake for another 7 minutes.

IMPORTANT Slide parchment with cookies onto work surface; cool cookies. Repeat with remaining batter, cooling sheets completely and lining with clean parchment for each batch.

In the top half of a double boiler whisk sugar and egg white..... in the bottom half of the double boiler add 2 C of water bringing it to a simmer using medium to high heat.... Place the top half of the double boiler over the bottom half... heating the mixture while whisking occasionally about 4-6 minutes.

Remove the top half of the double boiler from the heat, scraping the ingredients into the bowl of a stand mixer.... (use a whisk attachment).

Whip on medium-high speed until it is light, white, and cool to touch (4-6 minutes).

Reduce speed to low while adding one chunk of butter at a time.

Increase the mixer speed to medium... beating until the buttercream is smooth ( 4-5 minutes).....Add salt and vanilla extract. Mix well..

Using a pastry bag with a #5 tip add some of the buttercream to the flat side of the macaron.

Add another macaron on to the top of the first macaron, flat sides facing flat sides..... gently pressing the top macaron to fit in place evenly with the bottom one.