Ingredients

For the cupcakes:
• 2 1/4 cups cake flour
• 1 tablespoon baking powder
• 1/2 tsp salt
• 1 1/4 cup buttermilk
• 4 large egg whites
• 1 1/2 cups sugar
• 1 stick (8 tbsp) unsalted butter, at room temperature
• 1 tsp pure vanilla extract
• 1/2 tsp pure lemon extract
• lemon zest from two lemons
For the buttercream:
• 8oz. cream cheese
• 1/4 cup butter (1/2 stick)]
• 1 pint blackberries, pureed and strained (approximately 1/4 cup)
• 1/8 tsp lemon zest
• 3-4 cups powdered sugar
For the filling:
• Ina Garten's Lemon Curd

Instructions

For the cupcakes:
• Preheat oven to 350 degrees F. Line cupcake tins with paper liners or spray with nonstick spray.
• Sift together the flour, baking powder and salt. Set aside.
• In a medium bowl (or in a large measuring cup), whisk together the buttermilk milk and egg whites.
• In another bowl, combine the sugar and lemon zest and rub them together with your fingers until the sugar is moist and fragrant.
• Using a stand mixer with paddle attachment or hand mixer, cream butter and lemon sugar mixture until light and fluffy.
• Add extracts and beat until well combined.
• With mixer on medium, alternate adding the dry mixture (flour & baking powder) and the wet mixture (eggs and buttermilk) in thirds, until well combined.
• Put the the batter into the cupcake tins and bake for 18-22 minutes, or until the cupcakes are well risen and springy to the touch – a toothpick inserted into the centers should come out clean. Cool on wire rack
For the buttercream:
• Cream cream cheese and butter until light and fluffy.
• Add blackberry puree and lemon zest and mix until well combined.
• Add powdered sugar in half cup increments until desires sweetness and consistency are reached.
For the Lemon Curd:
• See Ina Garten's Lemon Curd Recipe
• Note: After reading the reviews I decided to reduce the sugar to 1 cup, especially since the curd was going to be used in a cupcake. It turned out great and will be a nice tart bite to contrast the sweet fluffy cupcakes. I used Ina's method, however my food processor is stuck in storage so I had to use a blender. If you're in the same boat, add a little of the lemon juice to the blender with the zest to help it along. Also, Ina's recipe says the curd will set in about 10 minutes, but for me it took closer to 25 minutes over low hear for the mixture to thicken. I recommend upping the cooking temperature to medium-low to quicken the process - but make sure you stir constantly!