Ingredients

7 Lb American Almond Macaroon,  Almond or Kernel Paste 
1 Lb 12 Oz Whole Eggs (A)
7 Lb Granulated Sugar 
1 3/4 Oz Salt  
3 Lb 8 Oz Unsalted Butter 
3 Lb 8 Oz Vegetable Shortening 
5 Lb 4 Oz Whole Eggs (B)
2 Oz Vanilla Flavoring 
1 Oz Rum Flavoring 
3 Lb 1 Oz Cake Flour 
Liquid Food Coloring as needed
Apricot Jam as needed
Rum as needed
Chocolate Glaze as needed

Directions

To make the Batter: Place the American Almond Macaroon Paste and 1 pound 12 ounces of the eggs (A) in the bowl of a mixer fitted with the paddle attachment.  Blend on low speed until the almond paste is smooth. Add the sugar and salt.  Cream the mixture.

Blend in the butter and then the shortening. Cream the mixture until smooth, light and aerated.  Add the vanilla and rum. Cream to light, fluffy batter. Scrape the bowl.

Gradually add the remaining eggs, scraping the bowl periodically as the eggs are blended into the batter. Beat on medium speed until well creamed, light and fluffy.

Add the flour mixing slowly until blended.

Divide the mixture evenly between three bowls. Lightly color one portion of the batter pink, one portion green, and leave the third portion plain (or lightly color with egg shade).

Prepare nine sheet-pans by greasing the edges and lining with parchment paper.

Scale 3 lbs. 8 oz. of each color batter onto a full-sheet pan. There will be three sheets of each color. Spread the batter evenly and as smooth as possible using a spatula.

Bake at 420°F until the cake feels springy to the touch, for approximately 10 to 12 minutes.  Be careful not to over bake.

When the sheets are cool enough to handle, but still slightly warm, after about 30 minutes, create the layered cookies. For each finished sheet of rainbow cookies, use three layers of the baked cake. Flavor the apricot jam with some rum. Spread a thin layer of the apricot jam on one of the plain cake layers. Use only enough just to moisten the cake. Invert a pink-tinted layer of cake on top. Remove the parchment paper then spread it with the apricot jam. Invert a green-tinted layer of cake on top.  Keep the parchment paper in place.

Compress the cake layers by placing a stack of clean sheet pans on top of the cake. Let the cake sit overnight. Then, refrigerate overnight for easier handling. You will have three, 3-colored sheets that may be kept frozen until needed.

To portion the rainbow cookies, place a 3-layer sheet on a cutting board. Brush off any loose cake crumbs and cover the top with melted chocolate glaze. When the chocolate has set, cut the sheet into 1 ¼-inch squares or divide the sheet into eight long strips and slice each strip into ¾-inch-wide slices. Cover with transparent film until served.

Formulation courtesy of American Almond