Vanilla Rainbow Cake Roll

Emily asked me if I would bake Garsha a birthday cake. I agreed, and then asked her what flavor cake and icing Garsha would like, suggesting some options. Emily told me that Garsha really preferred vanilla cake - she does not like chocolate cake.

Wait - what? Vanilla cake?

I don't believe I have ever baked a vanilla birthday cake - my family goes for chocolate cake, with various frosting flavors. Sometimes they go for pie, but never vanilla cake. So I started looking for vanilla cake recipes, and I saw a rainbow cake roll that needed to be tried. So I did.

Ingredients:

Rainbow Cake:

• 6 eggs 
• 1 box Betty Crocker SuperMoist White Cake mix
• 1/2 cup Greek yogurt (I used non-fat)
• 1 teaspoon vanilla extract
• 1/4 cup vegetable oil
• red, orange, yellow, green, blue and purple gel food color (or mix as needed)
• 1/2 cup powdered sugar

Vanilla Frosting:

• 35g (or 4½ tablespoons) all-purpose flour
• 200g (or 1 cup) granulated sugar
• pinch of salt
• 240ml (or 1 cup) milk
• 226g (or 2 sticks) unsalted butter, softened at room temperature
• 3/4 teaspoon vanilla extract
• 1 cup powdered sugar, divided

Chocolate Peanut Butter Mousse:

• 1/2 cup semi-sweet chocolate chips 
• 1 container tofu, silken or firm (approx 12 oz)
• 1/2 cup peanut butter (if using natural peanut butter, add 1/4 cup powdered sugar)
• 2 tablespoons cocoa powder
• 1/2 to 3/4 cup powdered sugar

Cake Instructions:

1. Heat oven to 350ºF. 
2. Make pudding base for vanilla frosting first so it can cool down.
3. Spray cooking spray on the bottom of one 11x17 inch half sheet pan and one 9x13 pan, line both with parchment paper, and light coat paper with cooking spray.
4. In stand mixer bowl, whisk eggs on high speed until thick and lemon-colored, about 4 minutes.
   
   
   
5. Add cake mix, Greek yogurt, and oil. Beat on low speed 30 seconds, then on medium speed for 1 minute.
6. Place batter into 6 bowls, about a cup batter per bowl,
7. Mix food color in each bowl to make red, orange, yellow, green, blue and purple.
   
   
   
   
8. Scoop each batter into one corner of quart sized plastic bag. Seal with a rubber band, and cut one 1/4” corner off each bag.
    
   
   
   
9. Starting with purple, pipe a 45 degree line of batter down from one corner of each pan. Aim for about a 1/2” wide stripe. (You can handle the bags fewer times by using alternating pans.)
10. Then add a blue, green, yellow, orange and red stripe, and repeat.
    (Work left to right, until right side is complete, then flip pan around to fill in last section.)
     
    
    
11. Bake 10 to 12 minutes or until top springs back when touched. 
12. While the cakes are baking, sprinkle powdered sugar over two clean kitchen towels.
13. Remove cakes from oven, turn one cake on to each kitchen towel. 
     
    
    
14. Peel away parchment paper. Immediately roll up cake and towel from narrow end.
    (I rolled up the excess towel, so there would be a center to fill in with frosting.)
    
15. Allow cakes to cool at least 30 minutes.
    (I put them on a baguette pan in the refrigerator to cool.)
     
    
    
16. Carefully unroll one cake; spread frosting or mousse on it it. Roll cake up into log; refrigerate at least 1 hour before serving. Repeat for the other cake.
    
 


17. Store covered in refrigerator.

Vanilla Frosting Instructions:

1. In a medium saucepan, whisk flour and granulated sugar together. 
2. Whisk in milk.
3. Heat over medium to medium-low, whisking all the time. 
4. After it comes to a boil, reduce heat and continue whisking until a pasty pudding forms, probably 2 minutes. Do not allow mixture to brown.
5. Remove from heat, and let cool 1 minute while whisking. 
6. Scoop pudding onto a plate, smooth, and cover with plastic wrap to keep a film from forming.
7. Let cool to room temperature. (You can cool part way in the refrigerator.)
8. Once the pudding has cooked. whip the softened butter in stand mixer on high for 5 minutes or so. Mix in 1/2 of powdered sugar (and the meringue powder if using.)
9. Add a tablespoon of the pudding at a time to the butter while still mixing.
   (Scrape down sides of bowl as needed.)
10. Add in vanilla and last 1/2 cup powdered sugar, mix in well.
11. Add in 2 to 3 tablespoons of colored jimmies.
    
    
12. Use to frost inside of cake roll - or refrigerate to use later. (Allow to come to room temperature and mix briefly loosen if using refrigerated frosting.)

Chocolate Peanut Butter Mousse Instructions:

1. Press excess water out of the tofu for a few minutes into a couple of paper towels. 
2. Melt the chocolate chips over low heat, stirring frequently to ensure the chocolate doesn't burn. (You can use a double boiler if you have one, or your microwave.)
3. Once the chocolate is melted, let it cool for a few minutes.
4. Whirr together the peanut butter, powdered sugar, cocoa powder and tofu in a food processor until smooth and creamy.
5. Whirr in the melted chocolate. 
6. Cover mousse with plastic wrap. Let chill a few minutes (or more) in the refrigerator.

Carole's Notes:

The cake was a hit for the youth group party! I was surprised, but the youth preferred the vanilla cake as well.



I really liked the taste of vanilla in the frosting - I will make the frosting again. I probably will use a scratch white cake recipe for the cake next time.

Ok, this cake is a bit of labor. Since I decided to use the mix recipe for the cake, I looked for a vanilla frosting recipe that sounded like it would be sturdy enough to be rolled, and then go to a pool party in Florida in May. When it turned out I needed more frosting for the second cake roll, I decided to improvise a chocolate peanut butter mousse.

Things I learned:

• Food color gels have a shelf life of 2 years or so after you open them.
• It is hard to get a pretty purple color with  old food gels.
• You lose some of the whipped volume when you divide the batter into 6 bowls and add food coloring.
• It is labor intensive to mix up separate colors, and pipe out rows of cake batter. Next time I will pipe a color into one pan, I will also pipe it into the second pan.
• The diagonal strip looks pretty in a roll.
• You can make a tasty tofu based mousse for a filling!

The cake recipe was lightly adapted from https://www.tablespoon.com/recipes/rainbow-cake-roll/e4ac075c-061d-4837-9c46-ba1d7be741cc#reviewDiv


The vanilla frosting was lightly adapted from http://thetoughcookie.com/2015/06/07/how-to-make-flour-buttercream-or-ermine-buttercream-the-battle-of-the-buttercreams-2-0/

The chocolate peanut butter mousse was lightly adapted from http://carolelikesroundfood.blogspot.com/2015/08/chocolate-peanut-butter-silk-pie-no-bake.html