Blackberry Lemon Cupcake with Graham Cracker Crust

Ingredients

• 11.5 g double-acting baking powder 
• 85 g blackberry puree 
• 0.5 cup garnish: blackberry jam for filling
• 375 g cake flour 
• 2 large eggs room temperature
• 2 large egg whites 
• 160 g graham crackers 
• 2  lemon zest 
• 6 g salt 
• 100 g sugar 
• 170 g butter unsalted room temperature
• 8 g vanilla extract 
• 244 g milk whole

Equipment

• food processor
• bowl
• frying pan
• oven
• whisk
• stand mixer
• measuring cup
• muffin tray

Directions

1. For the crust:Preheat oven to 350 degrees F. Line two 12-cup muffin tins with cupcake papers.Pulse graham crackers in food processor into fine crumbs.
2. Add butter and sugar and pulse until combined.
3. Place about 2 teaspoon of graham cracker mixture into the bottom of each cupcake paper. Use your fingers or a pastry tamper to press mixture firmly together.
4. Place muffin tins in oven and bake for 5 minutes.
5. Combine flour, baking powder, and salt in a medium bowl and set aside.
6. Combine milk and vanilla in a measuring cup and set aside.
7. Place butter and sugar in bowl of stand mixer. Cream together for 3-5 minutes until light and fluffy.
8. Add in eggs and egg whites one at a time, beating to fully combine before adding the next one.
9. Add in the flour mixture and milk in five alternating additions, starting and ending with the flour.
10. Mix just to incorporate before adding the next addition.Fill cupcake papers about 3/4 full with batter.
11. Bake for 16 to 20 minutes, rotating pans halfway through. Cupcakes should be just starting to turn golden on top and a tester inserted in the center should come out clean.
12. Combine egg whites and sugar in a metal bowl.
13. Place over a pan of simmering water.
14. Whisk the mixture constantly over heat until sugar is dissolved and mixture looks smooth and shiny. Continue whisking until the mixture reaches 160 degrees F.
15. Remove mixture from heat and pour into a stand mixer bowl.
16. Whisk on medium speed for about 5 minutes until the mixture has cooled.Switch to the paddle attachment and with the speed on low, add the butter a few pieces at a time, beating until smooth. Do not add the butter too quickly or beat too quickly or the buttercream may break.When all the butter has been added, beat the buttercream on medium-high speed for about 6-10 minutes until it is very thick and smooth. It may appear to separate briefly but continue beating and it should come back together.
17. Cut a small core out of the center of each cupcake. Fill with a spoonful of blackberry jam (you can also use fresh blackberry puree). Fill a piping bag with the buttercream and pipe a swirl on top of each cupcake.