Friday, January 08, 2021

Freeze-Dried Strawberry Cake


I was trying to figure out what to do with all the leftover freeze-dried strawberry powder I had left, besides make smoothies, and I happened on this recipe for a freeze-dried strawberry cake and frosting. The upside to freeze-dried fruit, in this case, is that it’s always in season, and it gives the cake and frosting a pink hue naturally – though in this case the cake is still enhanced with food coloring. I really liked this cake, and the Little Prince liked it so much that he wants me to make it again! (But I’m going to wait a while, because I *just* finished that strawberry powder!) 

I reordered the steps below the make the recipe easier to follow. I used store-bought egg whites for this because it’s called for in large-ish quantities in both the cake and the frosting. I didn’t have strawberry extract, so I just omitted it, and I used 2 drops of red gel food coloring in the cake, but you could omit it. Note that it’s really important to have ingredients at room temperature here! If you only have whole freeze-dried strawberries, you can use a food processor or spice mill to grind them to a fine powder, then sift the powder at the end to ensure consistency. 

For the cake 
10 oz (284 g) all-purpose flour 
1 oz (28 g) freeze-dried strawberries ground to a fine powder 
1 ½ tsp. baking powder 
1 tsp. baking soda 
½ tsp. salt 
zest of 1 lemon, finely grated 
1 cup (2 sticks) lactose-free butter, at room temperature 
10 oz (284 g) granulated sugar 
6 egg whites (for me this was 1 cup/8 oz), at room temperature 
1 cup lactose-free milk, at room temperature 
¼ cup (2 oz) vegetable oil 
1 tsp. vanilla extract 
1 tsp. strawberry extract 
1 drop pink food coloring (optional) 
1 drop red food coloring (optional) 

Adjust an oven rack to the middle position and preheat to 350 °F. Line 2 8”-round cake pans with parchment paper and grease them. 

In a medium bowl, whisk together the flour, freeze-dried strawberry powder, baking powder, baking soda, salt, and lemon zest. Set aside. 

In the bowl of a stand mixer, beat the butter at medium-high speed until smooth and shiny, about 30 seconds. Gradually sprinkle in the sugar, beating until mixture is fluffy and almost white, about 3-5 minutes. Add the egg whites approximately two at a time, beating 30 seconds between each addition. 

Combine the milk, oil, vanilla extract, strawberry extract, and food coloring in a separate medium bowl.  

With the mixer at the lowest speed, add about a third of the dry ingredients to the batter, followed immediately by about a third of the milk mixture; mix until ingredients are almost incorporated into the batter. Repeat the process 2 more times. When the batter appears blended, stop the mixer and scrape the sides of the bowl with a rubber spatula. 

Divide the batter evenly between the prepared pans. Smooth the tops with a rubber spatula. Bake cakes until they feel firm in the center and a toothpick comes out clean or with just a few crumbs on it, about 35-40 minutes. 

Transfer pans to a wire rack and let cool for 10 minutes. Invert cakes onto the rack and pop cakes out of pans. Cool completely before frosting. 

For the frosting (I halved the original quantities, and this here is enough for the cake) 
½ cup pasteurized egg whites, at room temperature 
1 lb. powdered sugar, sifted 
1 lb. (4 sticks/2 cups) lactose-free butter, at room temperature 
½ tsp. vanilla extract 
¼ tsp. salt 
½ oz freeze-dried strawberry powder (see note above) or more, to taste 
½ tsp. finely grated lemon zest 

Place egg whites and powdered sugar in a mixing bowl with the whisk attachment. Whisk to combine. 

Add in butter in small chunks, then vanilla and salt. Whip on high until light and fluffy and white.

Add freeze-dried strawberry powder and lemon zest to buttercream. Whip until combined. 

(Buttercream can be stored in the fridge until you are ready to decorate; just let come to almost room temperature and re-whip before frosting.)

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