Using a permanent marker, draw 2-inch circles 1 inch apart on 2 sheets of parchment paper (24 per sheet). Place parchment, marker side down, on 3 rimmed baking sheets.
In a medium bowl, sift together almond flour and confectioners' sugar.
In the heatproof bowl of a stand mixer, whisk together egg whites and granulated sugar by hand until frothy. Place bowl over a small saucepan of simmering water. Cook, whisking constantly, until sugar completely dissolves, mixture is warm to the touch, about 2 minutes.
Carefully return bowl to stand mixer. Using the whisk attachment, beat at high speed until stiff peaks form. Add a small amount of green gel food coloring, beating until desired color is reached. Fold in flour mixture.
Transfer batter to a pastry bag fitted with a medium round piping tip (Ateco #803). Pipe batter onto drawn circles until batter just reaches drawn circle. Move and lift tip in a quick circular motion as you finish piping each macaron shell.
Firmly tap pans vigorously on counter 5 to 7 times to release air bubbles. Sprinkle with pistachios. Let stand at room temperature until a skin forms on top, 1 to 2 hours.
Preheat oven to 300°F (150°C). Bake, one pan at a time, until firm but wobbles slightly at the touch. 20 to 25 minutes. Let cool completely on pans.
Remove cooled macaron shells from pans. Turn half of shells flat side up.
In the bowl of a stand mixer fitted with the paddle attachment, beat butter at medium speed until creamy, 2 to 3 minutes. Gradually add confectioners' sugar, pistachios, and salt, beating until smooth.
Add a small amount of food coloring; beat until well combined, light, and fluffy, about 2 minutes. Use immediately.
In a medium saucepan, bring raspberries, granulated sugar, and lemon zest and juice to a boil over medium heat, stirring occasionally until sugar dissolves. Reduce heat and simmer for 5 minutes.
Transfer mixture to the container of a blender, and blend until smooth. Strain mixture through a fine-mesh sieve, discarding solids. Return mixture to saucepan, and heat over medium heat.
In a medium bowl, whisk together egg yolks, cornstarch, and salt. Add about one-fourth of hot raspberry mixture to egg yolk mixture, whisking constantly.
Whisk egg yolk mixture into remaining hot raspberry mixture in pan. Cook over medium-high heat, whisking constantly, until thickened, 5 to 7 minutes.
Remove from heat; whisk in butter 1 tablespoon (14 grams) at a time, until melted and smooth. Cover and refrigerate until thick and cold before using, at least 2 hours or up to 1 week.
Fill center of buttercream border with curd (about 3 grams each). Gently top with remaining shells, flat side down.
