Recipe: Blueberry and Custard Sheet Cake

So, yesterday was G's birthday! πŸŽ‰

If you don't know, I'm really into birthdays and celebrating them. It's important to take some time, do the things you like to do, eat good food, and celebrate a little bit. G and I both had off on Monday so we spent a quiet morning at home while I baked this cake, made a trip to Reading Terminal Market to get Beiler's Donuts and eat lunch, cleaned up around the house and watched some TV together, opened gifts, and then went to the movies. A simple day, but the weather was lovely and it was just nice to relax.

For the past 3 weeks or so, G and I have been avidly watching The Great British Baking Show (starting with the first season) and it's safe to say I'm definitely obsessed with it. So after a few days of me pestering G about what he wanted his birthday cake to be, he finally said "I want whatever that is on the tv!" and this cake idea was born. It's a standard vanilla sheet cake, topped with a creamy custard, fresh blueberries, and whipped cream. Simple, but different, and very tasty.

Blueberry and Custard Sheet Cake

Yields 15-20 pieces

2/3 cup sugar
1/4 cup cornstarch
1/2 teaspoon salt
3 cup milk
2 eggs, lightly beaten in a small bowl
1 1/2 teaspoon vanilla extract

1 1/2 sticks butter, room temperature
1 1/2 cup sugar
3 large eggs, room temperature
1 cup all-purpose flour
1 cup cake flour
1 teaspoon baking soda
1 teaspoon baking powder
1/4 teaspoon salt
1 cup buttermilk
1 teaspoon vanilla extract

Whipped Cream
2 cups heavy whipping cream
2 tablespoons powdered sugar
1 teaspoon vanilla extract
2 pints of blueberries

Make the custard: In a large saucepan, whisk sugar, cornstarch, salt, vanilla extract, and milk until smooth. Cook and whisk over medium heat until thickened and bubbly, about 10 minutes. Once thickened, reduce heat to low and cook for 2 minutes longer, whisking the entire time. Before adding in the eggs, you'll need to temper them. Take 2-4 spoonfuls of the heat mixture and whisk it into the eggs, gradually raising the temperature of the eggs so they don't scramble. Repeat with 2-4 more spoonfuls before adding all the egg mixture into the pan. Bring to a gentle boil and cook for 4 minutes longer, whisking the whole time. Final mixture should be thick without lumps and a light yellow color. Pour into a large bowl, press plastic wrap across the top so it doesn't form a skin and let cool completely in the fridge for at least an hour. I left mine in overnight. When you remove the custard from the fridge, give it a good whisk before using it.

Make your cake: Preheat oven to 350 degrees and prepare a baking pan with butter. Line the bottom of the pan with parchment paper and then butter on top.

In the bowl of an electric mixer, cream butter and sugar for 5 minutes until light and fluffy. Scrape down the bowl and add in eggs, one at a time, until combined.

In a separate bowl, sift both flours, baking powder, baking soda, and salt to remove and clumps and combine ingredients. Mix in 1/3 of the dry ingredients to the creamed butter, then mix in half of the buttermilk and all of the vanilla extract until just combined. Repeat with another 1/3 of dry and the rest of the buttermilk, and then add in the final dry ingredients. Careful not to over mix. Pour mixture into the prepared baking sheet and spread evenly with a rubber spatula. Bake for 30-40 minutes or until the top if golden brown and a toothpick inserted comes out clean. Let cool completely.

Make your whipped cream: In the bowl of an electric mixer, mix whipping cream on high until sift peaks form. Add in powdered sugar and vanilla and mix until combined.

Assemble your cake: Once your cake has cooled, spoon the custard over the top of the cake using a rubber spatula to even out that layer. Press blueberries into the custard in a stripe pattern so they are evenly distributed on the cake. Top with a layer of whipped cake and enjoy! 

Because this cake is covered in whipped cream and custard, store any leftovers in the fridge and best served chilled. 

A Blueberry and Custard Sheet Cake for a Birthday!