Because Why Not – Peanut Butter and Strawberry Jam Cake with Peanut Butter Swiss Buttercream Frosting

This joyful looking cake came into existence for two reasons. First, apparently I loved making chocolate desserts too much and I must stay away from it (right?). Second, it doesn’t hurt to go for some classic sometimes. By classic, I mean the marriage of salty and sweet – Peanut Butter & Jelly – made famous by Americans. Of course, this combination shouldn’t be limited to a breakfast/snack sandwich; think about it, if it works brilliantly between two slices of bread, it surely can make a great cake too.

I originally designed this layer cake for my friend’s birthday, and this is a new recipe modified mainly to improve the cake’s texture. My first PB&J cake was bit on the dry and tough side. Therefore, in my second attempt, I put in more eggs and oil, and I also decided to fold meringue into the cake batter at last instead of incorporating whole eggs. Such changes increased the volume of the cake with richer taste and finer structure.

One indispensable component of this cake is the jam. The slightly tart strawberry jam with a citrus touch perfectly undercuts the richness of the buttercream. People who have been in my baking life would know that I always prefer making things from scratch, for I want to have great control of my baked goods (here comes the even greater satisfaction afterwards!). I couldn’t resist making my own strawberry jam for the cake (see note for instructions), but again, you can by all means purchase your favourite jam :). Enjoy!

Ingredients:

(make one 6-inch cake)

For the Cake:

• 1 ½ cup (188g) cake flour
• 1 tsp baking powder
• ¼ tsp baking soda
• ¼ tsp cinnamon
• Pinch of salt
• ¼ cup (58g) unsalted butter, softened
• 2 tbsp (30ml) vegetable oil
• 1/4 cup (60ml) crunchy peanut butter
• ⅓ cup (75g) granulated sugar
• 2 egg yolks
• 2 egg whites + 25g icing sugar
• 1 tsp vanilla extract

For the Peanut Butter Swiss Buttercream Frosting:

• ¾ cup (150g) white granulated sugar
• 5 egg whites
• 1/4 tsp cream of tar tar
• 1 ½ ( (345g) cups unsalted butter, softened  
• 1 teaspoon vanilla extract
• 1/4 cup (60ml) creamy peanut butter

For the homemade strawberry jam (or ½ cup store bought jam)

• 250g  strawberries
• 4 tbsp white sugar
• 1/2 lemon, juice and zest of

Toppings:

• Fresh strawberry slices
• Extra peanut butter swiss buttercream

Instructions:

For the cake:

1. Preheat the oven to 350F (175C)
2. Line one 6 inch cake with parchment paper. Set aside.
3. In a mixing bowl, thoroughly sift in and combine flour, baking powder, baking soda, cinnamon and salt.
4. In another mixing bowl (make sure it’s oil free), add egg whites, icing sugar and cream of tar tar. Using an electric beater, beat on high speed until soft peak forms. Transfer the meringue into another bowl; set aside.  
5. Using the same mixing bowl you used to make the meringue, beat butter and sugar at medium-high speed for 4-5 mins until pale and fluffy. Add oil and continue beating for 2 min until incorporated.
6. Add eggs yolks, one at a time, peanut butter and vanilla. Continue to beat at medium speed until well combined.
7. Add the prepared dry ingredients into the mixture in three batches. Mix on low speed until no flour can be seen.
8. Finally, gently fold the prepared meringue into the cake batter with a spatula. Mix gently with folding motion until just incorporated.
9. Pour the mixture evenly into the prepared cake tin. Tap the pans several times to break any air bubbles. Bake for 50 mins, or until a toothpick inserted in the cake’s centre comes out clean.
10. Cool the cake for 30 minutes in their pans, then take them out and put them onto a cooling rack to cool completely.
11. While the cakes are cooling, prepare the peanut butter swiss buttercream.

For the Peanut butter Swiss Buttercream:

1. Add  egg whites and sugar to an oil-free bowl. Using a double boiling method, gently heat the egg whites mixture up, while whisking constantly, until temperature reaches 140F (60C).  The sugar should have completely dissolved at this stage.
2. Add the hot egg white-sugar mixture to your electric mixer mixing bowl (oil-free). Whip on high speed until the meringue is thick and glossy, and the bottom of the bowl feels cool. This will take about 7-10 mins.
3. Turn to medium-low speed, gradually add the softened butter cubes, one at a time, until incorporated. Continue beating until a silky smooth texture is reached. Add vanilla and peanut butter, and beat until well combined.
4. Pipe the buttercream onto the cupcakes with a round tip for later use.

Assembly:

1. Level the cake layers by slicing the top curve of the cakes with a sharp knife to achieve a flat surface.
2. Cut the cake into three even layers.
3. Peel the parchment paper from the base of the cake layers and place one layer onto a plate or a cake board placed on a revolving cake stand (if you have it).
4. Now we do the crumb coat first.
5. Pipe a generous amount of frosting evenly on the cake layer. Using an offset spatula, spread the frosting carefully and top it a thin layer of strawberry jam.
6. Top it with the second cake layer and repeat step 5, and top it with the third cake layer.
7. Frosting the top and sides of the cakes. Get a nice, smooth coat of icing with a bench scraper or a spatula.
8. Put the crumb-coated cake in the refrigerator for an hour to get the frosting nice and firm. Once the cake is chilled, frost your cake evenly with another layer of frosting using the same method. Get rid of all the peaks and blemishes in the process.
9. Pipe dollops of cream onto the cake, put thin strawberry slices and spinkle cocoa powder as garnish if desired.
10. Refrigerate the cake for at least 1 hour.

Note:
Instructions for the homemade strawberry jam: 

1. Prepare the strawberries by washing them and drying them with a kitchen towel. Remove their stems. Crush strawberries in batches or cut them into small cubes.
2. In a heavy bottomed saucepan, mix together the strawberries, sugar, and lemon juice. Stir over low heat until the sugar is dissolved. Increase heat to high, and bring the mixture to a full rolling boil. Boil for 5-10 mins until the jam has reached 105C, then turn off the heat.
3. Let the jam cool to room temperature. Put the jam into jars and refrigerate until ready for use.

Yum