01 -
Place oven rack on the middle setting and preheat the oven to 350°F (177°C). Grease and flour (or use homemade cake release) two 8-inch or 9-inch round cake pans.
02 -
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
03 -
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together until light and fluffy, about 2-3 minutes. Add vanilla and mix to combine.
04 -
Add the eggs and egg white one at a time, mixing after each addition. On low speed, alternate adding the flour mixture in two parts with the milk, beginning and ending with the flour mixture.
05 -
Blot the strawberries dry to remove excess moisture and gently fold them into the batter by hand.
06 -
Divide the batter evenly between the prepared pans. Bake for 40-44 minutes, or until a toothpick inserted into the center comes out clean and the tops are lightly browned. Allow cakes to cool completely in the pans on a wire rack.
07 -
Using a blender or food processor, process the freeze-dried strawberries into a fine powder. In a large bowl using a handheld mixer or a stand mixer with the paddle attachment, beat the butter on medium speed until creamy, about 2 minutes. Add powdered sugar, vanilla, and milk or cream. Add strawberry powder and salt, then mix on medium speed until smooth, about 3 minutes. Adjust consistency by adding more milk or powdered sugar as needed.
08 -
Trim the tops of the cooled cake layers for a flat surface. Place one layer on a cake stand or plate, spread a layer of strawberry buttercream on top, then place the second layer cut-side down. Spread more buttercream on the top and sides of the cake.
09 -
Serve the cake or refrigerate for about 10 minutes before slicing for cleaner cuts. Store leftovers covered tightly at room temperature for up to 5 days or in the refrigerator for up to 1 week.