2 cups plus 1/3 cup unsalted butter, softened and divided
2 1/4 cups plus 2 tablespoons sugar, divided
2 large eggs
2 vanilla beans, split lengthwise, seeds scraped and reserved, divided
4 cups all-purpose flour
1 1/4 teaspoons kosher salt, divided
1/4 teaspoon green gel food coloring
1/4 teaspoon violet gel food coloring
1/16 teaspoon yellow gel food coloring
1 drop brown gel food coloring
3 cups whole milk
8 egg yolks
1/4 cup plus 3 tablespoons cornstarch
Preheat oven to 350°. Line 3 baking sheets with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, beat 2 cups butter and 1 182 cups sugar at medium speed until creamy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition. Beat in seeds from 1 vanilla bean.
In a large bowl, whisk together flour and 1 teaspoon salt. With mixer on low speed, gradually add flour mixture to butter mixture, beating just until combined. Divide dough in half. Place one half on one prepared pan. Cover with plastic wrap, and press to ?-inch thickness. Freeze until firm to the touch, about 15 minutes.
Bake until edges and top are lightly golden, about 15 minutes. Let cool completely on pan. Using a 2 1/4-inch round cutter, cut 12 cookies.
Divide remaining dough into 3 small bowls. Using food coloring, tint one green, one purple, and one gold (yellow and brown). Refrigerate for 30 minutes.
Using a 1 1/2-tablespoon spring-loaded scoop, scoop 8 cookies of each color, and place on remaining 2 prepared pans; gently flatten cookies.
Bake until edges are lightly golden, about 12 minutes. Let cool on pans for 2 minutes. Remove from pans, and let cool completely on wire racks.
In a medium saucepan, heat milk, 1/2 cup sugar, and remaining 1 vanilla bean and seeds over medium-low heat.
In a medium bowl, whisk together egg yolks, cornstarch, remaining 1/4 cup plus 2 tablespoons sugar, and remaining 1/4 teaspoon salt. Gradually add hot milk mixture to egg mixture, whisking constantly. Strain mixture back into pan, and cook over medium heat, whisking constantly, until thickened. Strain pastry cream through a fine-mesh sieve into a medium bowl, discarding solids. Stir in remaining 1/3 cup butter. Cover with a piece of plastic wrap, pressing wrap directly onto surface of cream. Refrigerate for at least 1 hour or up to 4 days.
In the bottom of 12 (4-ounce) jars, place 1 plain cookie. Whisk chilled custard smooth; pipe or spoon custard on top of each cookie in jars. Crumble colored cookies on top of custard. Cover and refrigerate until ready to serve.