1 cup (4 ounces),plus 2 tablespoons cake flour
3 tablespoons malted milk powder
1-1/2 teaspoons baking powder
1/4 teaspoon fine sea salt
3 sticks (12 ounces) unsalted butter, softened
1 cup (8 ounces) condensed milk
5 large eggs, room temperature
12 large egg yolks, room temperature
1 cup (7 ounces) granulated sugar
2 teaspoons pure vanilla extract
2 teaspoons pure almond extract
Food gel coloring: red, orange, yellow, green, blue, purple
1. Adjust oven racks to middle position and heat oven to 450 degrees. Line one 8-inch square baking pan with parchment sling (allowing a 2-inch overhang on 2 sides). Set aside.
2. Add flour, milk powder, baking powder and salt to a small bowl, whisk to combine; set aside.
3. Place butter in bowl of standing mixer fitted with paddle attachment and beat at medium-high speed until creamy, about 1 minute. Add condensed milk and continue to beat until light and fluffy, about 5 minutes. Remove butter mixture into a medium bowl with a rubber spatula as clean as possible.
4. Replace paddle attachment with whisk attachment, Place eggs and egg yolks into bowl of stand mixer and whisk on medium-high speed for 1 minute. Slowly add sugar and continue to whisk until ribbon stage, about 6 minutes.
5. Reduce speed to medium and add butter mixture in three batches, until combined. Add extracts and increase speed to medium-high and whisk until fully combined, about 2 minutes. (Mixture might look curdled). Remove bowl from mixer and whisk in flour mixture with the whisk attachment of the mixer until just combined.
6. Divide batter into 6 equal portions; add food coloring to each portion to achieve desire color. Set aside.
7. Heat the prepared cake pan in the oven for 4 minutes. Remove pan from oven and spread half of purple color batter in the pan (about 5 tablespoons). Spread batter to coat the entire pan by tilting cake pan; bake for 3-4 minutes or until slightly brown.
9. Remove pan from oven, press cake layer with the bottom of a 1/2-cup measuring cup to remove excess air. Spread half of blue batter into pan over the purple layer, spread the batter to coat the entire pan by tilting cake pan; bake for 3-4 minutes or until slightly brown.
10. Continue step 9 with green, yellow, orange and red layer, then repeat the color again to achieve a total of twelve layers.
11. Remove cake pan from oven and set on cooling rack, cool cake in pan to room temperature, about 60 minutes. Lift cake out of pan with parchment sling. Cut into cubes, approximately 1-inc