3/4 cup all-purpose flour
3/4 cup cake flour
1 tsp baking powder
1/8 tsp baking soda
1/4 tsp salt
3/4 cup granulated sugar
1 Tbsp lemon zest (zest of 2 medium lemons)
1/2 cup unsalted butter , softened
1 large egg
2 large egg whites
1/2 tsp vanilla extract
1/2 tsp lemon extract (optional, for slightly stronger lemon flavor)
1/4 cup + 3 Tbsp buttermilk
1 1/2 Tbsp fresh lemon juice
1 Tbsp fresh lemon juice
1 Tbsp sugar
Raspberry Buttercream Frosting
1 (heaping) cup fresh raspberries
1/2 cup unsalted butter , nearly at room temperature
1/4 cup salted butter , nearly at room temperature
2 3/4 - 3 cups powdered sugar
1/2 tsp vanilla extract
24 fresh raspberries , for topping
Lemon wedges , for topping
Preheat oven to 350 degrees. Sift all-purpose flour and cake flour into a mixing bowl. Add baking powder, baking soda and salt and whisk 20 seconds, set aside.
In a food processor, pulse together 3/4 cup granulated sugar with lemon zest until finely ground, about 1 minute. In the bowl of an electric stand mixer fitted with the paddle attachment, whip together butter with lemon sugar mixture until pale and fluffy (if you don't have the paddle attachment that constantly scrapes bowl, then occasionally throughout entire mixing process, stop mixer and scrape down sides and bottom of bowl). Mix in egg, then mix in egg whites one at a time, adding in vanilla (and lemon extract if using) with second egg white.
In the liquid measuring cup used to measure buttermilk, whisk together buttermilk and lemon juice. Working in three separate batches, beginning and ending with flour mixture, add 1/3 of the flour mixture alternating with 1/2 of the buttermilk mixture and mixing just until combined after each addition. Divide batter among 12 paper lined muffin cups. Bake in preheated oven until toothpick inserted into center of cupcake comes out clean, about 18 - 20 minutes. Remove from oven and allow to cool several minutes in muffin tin, then transfer to a wire rack to cool slightly. Meanwhile prepare simple syrup.
For the simple syrup:
In a small bowl, whisk together 1 Tbsp lemon juice with 1 Tbsp granulated sugar until sugar has dissolved. Brush mixture over warm cupcakes (use all of it, about 2 light coats over each cupcake). Allow cupcakes to cool completely, meanwhile prepare raspberry puree and allow to cool.
For the frosting:
Puree raspberries in a food processor until well pureed then force through a fine mesh strainer into a bowl to remove seeds (you should have 6 - 7 Tbsp puree). Heat mixture in a saucepan set over medium-low heat until reduced by half (to 3 - 3 1/2 Tbsp). Cool completely (speed chill in freezer).
In the bowl of an electric stand mixer fitted with the paddle attachment, whip butter until very pale and fluffy. Mix in 1 cup powdered sugar then mix in reduced raspberry puree and vanilla. Add remaining powdered sugar and mix until light and fluffy (if an even stronger raspberry flavor is desired you can add in 1/4 tsp raspberry extract, or to taste).
Add one raspberry to top of each cupcake then pipe frosting over raspberry and top with another raspberry and a small lemon wedge (and straws for decoration if desired, I cut mine into thirds. Mint leaves are also optional). Store in an airtight container.