Directions:
Make the reduced strawberry puree and allow it to cool completely. See note.
Preheat the oven to 350°F (177°C). Grease and lightly flour two 9-inch cake pans.
Whisk the cake flour, baking powder, baking soda, and salt together. Set aside.
Using a handheld or stand mixer fitted with a whisk attachment, beat the butter and sugar together on high speed until smooth and creamed, about 2 minutes. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Beat in the egg whites on high speed until combined, about 2 minutes. Then beat in the sour cream and vanilla extract. Scrape down the sides and up the bottom of the bowl as needed. With the mixer on low speed, add the dry ingredients until just incorporated. With the mixer still running on low, slowly pour in the milk *just* until combined. Do not overmix. Whisk in 1/2 cup of reduced strawberry puree, making sure there are no lumps at the bottom of the bowl. The batter will be slightly thick.
Pour batter evenly into cake pans. Bake for around 24-25 minutes or until the cakes are baked through. To test for doneness, insert a toothpick into the center of the cake. If it comes out clean, it is done. Allow cakes to cool completely in the pans set on a wire rack. The cakes must be completely cool before frosting and assembling.
Make the frosting: Using a blender or food processor, process the freeze-dried strawberries into a powdery crumb. You should have around 1/2 cup. Set aside. In a large bowl using a hand-held or stand mixer fitted with a paddle or whisk attachment, beat the cream cheese for 1 minute on high speed until completely smooth and creamy. Beat in the butter until combined. Add the confectioners’ sugar, strawberry powder, 1 Tablespoon milk, and vanilla and beat on medium-high speed until combined and creamy. Add 1 more Tablespoon of milk to slightly thin out, if desired. Taste, then add a pinch of salt if needed.
Assemble and frost: First, using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface. Discard (or crumble over ice cream!). Place 1 cake layer on your cake stand or serving plate. Evenly cover the top with frosting. Top with 2nd layer and spread the remaining frosting all over the top and sides. Refrigerate for at least 45 minutes before slicing. This helps the cake keep its shape when cutting– it could slightly fall apart without time in the fridge.
Cover leftover cake tightly and store in the refrigerator for 5 days.
Make ahead tip: The cake layers can be baked, cooled, and covered tightly at room temperature overnight. Likewise, the frosting can be prepared then covered and refrigerated overnight. Light it sit at room temperature to slightly soften for 10 minutes before assembling and frosting. Frosted cake can be frozen up to 2 months if you have room in the freezer. Thaw overnight in the refrigerator and bring to room temperature before serving.
Recipe Notes:
*I strongly suggest using cake flour in this recipe. It’s sold right next to the all-purpose flour in the baking aisle. And you use it a lot in my recipes! In a pinch, you can use a DIY version: measure 1 cup of all-purpose flour. Remove 2 Tablespoons. Mix in 2 Tablespoons of cornstarch. Sift it. Measure 1 cup. This sifted 1 cup equals 1 cup of cake flour. I suggest doing this 3x, then remove 1/2 cup since you need 2 and 1/2 cups in this recipe.
Where to buy freeze-dried strawberries? I always find them in my regular grocery store in the dried fruit aisle. Wegmans, Giant, Trader Joe’s and Target carries them. Keep your eyes peeled– they’re more commonly found that you think! Do not use the chewy/gummy dried strawberries. You need FREEZE-dried strawberries which grind into a powder. If you can’t find them anywhere, just leave them out of the frosting and add another 1/2 cup of confectioners’ sugar.
*To make the reduced strawberry puree: puree 1 lb of strawberries. You should have a little over 1 cup. Stirring occasionally, simmer the puree over low-medium heat for 25-30 minutes until you’re left with 1/2 cup or a little over 1/2 cup Allow to cool completely before using in cake batter. I always make the reduced puree the day before so it has plenty of time to cool down. I cover and place in the refrigerator overnight. Use 1/2 cup in the cake. Discard any leftovers or spoon on ice cream/yogurt/add to smoothie. Yum!
*To bake in a 9×13 pan: Simply pour the batter into a greased and lightly floured 9×13 pan and bake for 40 minutes or until a toothpick inserted in the center comes out clean.
*Cupcakes: Fill cupcake pans 2/3 full with batter. Bake for 20-22 minutes. Makes 2 and 1/2 dozen cupcakes. For less cupcakes, you can make vanilla cupcakes, reduce the milk and sour cream to 1/3 cup each and add 1/4 cup of concentrated strawberry flavor to the batter.
From: https://sallysbakingaddiction.com/2018/01/05/strawberry-cake
