Sheet Pan Rainbow Cookie Cake

Preheat the oven to 350°F. Line an 18-by-13-inch sheet pan with parchment paper, spray the bottom and sides with nonstick cooking spray and set aside. 

In a large bowl, make the 2 boxes of cake mix according to the package directions, adding the almond extract with the wet ingredients.  

Divide the batter into three separate bowls and add food coloring to each until the desired shades of pink, green and gold are achieved (I like the look of the gold, but if you prefer, you can keep skip it and leave the third layer white). 

Pour the batter into the prepared sheet pan by pouring each color into a third of the pan, starting at the short end on the left and moving to the right (see Tip above). Spread out the batter, keeping the sections separate and cleaning the spatula after touching each color. 

Bake the cake until a toothpick inserted in the middle comes out clean, 20 to 25 minutes. Let cool in the pan for about 10 minutes before turning it out onto a cooling rack. Reserve the pan and parchment paper for assembly later. Let the cake cool completely before assembling. 

To assemble the cake, use a serrated knife to cut each of the three colored sections into its own rectangle. (This doesn't have to be perfect, and the sections can also be trimmed to your liking. I left a little multi-color swirl on mine.) Trim the uneven top part off of each section so it is as even as possible for stacking purposes. 

Place the wire cooling rack over the sheet pan and place the red section of the cake on the rack. This will be the bottom layer of the cake. Spread ½ cup of the raspberry jam on top of the red layer. 

Place the white/gold layer on top of the jam. Spread the remaining ½ cup jam on top of the white/gold layer. Place the green layer on top of the jam trimmed-side down so that the smooth side faces up. If the cake layers are misaligned, you can trim the cake as needed with the serrated knife. 

To make the ganache frosting, place the chocolate chips in a medium heatproof mixing bowl. In a small saucepan, heat the cream over medium-high heat until it reaches a light boil, then immediately remove it from the heat so it doesn't boil over. 

Pour the hot cream over the chocolate chips and whisk until completely smooth. Let the ganache cool for about 15 minutes so it won't readily slide off the cake's surface. Pour it slowly over the cake, letting it drip over the sides. Use an offset spatula or other tool as needed to cover the entire cake with a smooth layer of ganache.  

Let the ganache set for about 30 minutes on the counter. (You can keep the ganache smooth and shiny by not touching it!) Transfer the cake to a plate or platter by carefully sliding two large spatulas under each side of the cake and then gently lifting and moving it. Cut into slices and serve.