Prepare baking sheets with silicon baking mats or line with parchment paper.
Put the almond flour and powdered sugar into a food processor and pulse until combined or sift into bowl and whisk together. Sift the mixture 3 times.
Whisk the egg whites in a stand mixer on medium low speed until foamy. Add cream of tartar and whisk again on medium speed until soft peaks form. Reduce speed to medium low and slowly add the sugar. After about 15 seconds, increase the speed to high and whisk until really stiff peaks form. Fold in vanilla extract and food coloring.
Once stiff peaks have formed, sift ⅓ of the dry mixture over the egg whites and fold. Repeat until the mixture is combined and ribbons down from the spatula.
Put the batter in a pastry bag with a ½ inch plain round tip.
Pipe mixture onto prepared baking sheets in 2 inch circles, 1 inch apart. Tap the sheets on a surface twice. Preheat oven to 300 degrees.
Let the macarons sit at room temperature until dry to touch.
Bake 1 sheet at a time for 13 minutes, rotating halfway through.
While macaron shells are cooling, make the filling.
For the Lemon Curd Filling:
In a small heavy saucepan over medium heat, whisk eggs, egg yolk and sugar together. Slowly mix in lemon juice until blended. Add butter and lemon zest; cook, whisking constantly, until mixture is thickened and coats the back of a metal spoon(170°F). Strain into a small bowl; cool 10 minutes. Refrigerate, covered, until cold.
For the Meringue Topping:
In a large heatproof bowl, whisk together the egg whites, sugar, and cream of tartar, then set the bowl over a saucepan filled with just two inches of simmering water over medium heat. Do not let the bottom of the egg bowl touch the water. Whisk the eggs and sugar constantly until sugar is dissolved and mixture has reached a temperature of 160°F, about 4 minutes. The mixture will be thick and tacky at first, then thin out and become frothy.
Transfer the hot egg mixture to a stand mixer fitted with the whisk attachment. Beat on high speed until stiff, glossy peaks form, about 4 to 5 minutes.
Assembly:
Pair up your shells. On the bottom side of one, pipe lemon curd. Place on the top shell. Pipe on meringue to that top shell and toast with a blow torch.