Fresh Strawberry Layer Cake

Before you start

Most bright pink strawberry cakes owe their color to flavored gelatin. This one gets both flavor and a soft rose color from fresh strawberries puréed and simmered until they reduce to a thick, jammy concentrate. Reducing drives off water, which is the reason raw purée makes cakes gummy and frosting split, while keeping the fruit flavor intense enough to taste through butter and sugar.

The cake itself is a white butter cake made with egg whites only, so the crumb stays pale enough to show the pink. Expect a muted, natural shade rather than candy pink. Cool the reduction completely before it goes into either the batter or the buttercream; warm purée melts butter and ruins both textures.

Ingredients

• Strawberry reduction680 g (about 1½ lb) fresh or thawed frozen strawberries — hulled
• Cake300 g (2¾ cups, sifted) cake flour
• 300 g (1½ cups) granulated sugar
• 2½ tsp baking powder
• ½ tsp fine salt
• 170 g (¾ cup) unsalted butter — softened
• 4 large (about 120 g) egg whites — room temperature
• 120 ml (½ cup) strawberry reduction — from above, cooled
• 120 ml (½ cup) whole milk — room temperature
• 1 tsp vanilla extract
• Buttercream225 g (1 cup) unsalted butter — softened
• 400 g (about 3⅓ cups) powdered sugar — sifted
• 60 ml (¼ cup) strawberry reduction — cooled
• pinch fine salt

Method

1. Blend the strawberries to a smooth purée; you should have about 600 ml. Simmer it in a wide skillet over medium heat, stirring often and more constantly near the end, for 20 to 30 minutes, until it thickens like loose jam and measures 180 ml (¾ cup). Cool completely.
2. Heat the oven to 175°C (350°F). Butter the pans, line the bottoms with parchment and butter the paper.
3. In the mixer bowl, combine the cake flour, sugar, baking powder and salt. Add the softened butter in pieces and mix on low for about 2 minutes, until the mixture looks like damp sand.
4. Whisk the egg whites, 120 ml reduction, milk and vanilla in a jug. Add half to the flour mixture and beat on medium for 90 seconds to build structure, then add the rest in two parts, scraping the bowl after each.
5. Divide the batter between the pans (a scale helps; each takes roughly 620 g) and smooth the tops. Bake for 28 to 32 minutes, until the centers spring back and a toothpick comes out with a few moist crumbs.
6. Cool in the pans for 10 minutes, then turn out onto racks and cool completely, about 1 hour.
7. For the buttercream, beat the butter for 3 minutes until pale. Add the powdered sugar and salt on low, then beat on medium for 2 minutes. Add the remaining 60 ml reduction one spoonful at a time, beating well after each.
8. Level the layers if domed. Spread about a third of the buttercream over the first layer, set the second on top, and cover the top and sides with the rest. Chill for 20 minutes before slicing for clean cuts.

Tips for success

• Measure the reduction rather than trusting the clock. Stopping at 250 ml leaves too much water; going below 150 ml can scorch and turn the flavor brown and jammy.
• A wide skillet reduces the purée in about half the time a deep saucepan needs, and the larger surface lowers the risk of scorching.
• If the buttercream looks curdled after adding the reduction, the butter or the purée was too cold. Beat on high for a minute or warm the bowl briefly over hot water.

Substitutions

Cake flour

Use 270 g all-purpose flour plus 30 g cornstarch, sifted together. The crumb is slightly less fine but very close.

Fresh strawberries

Frozen unsweetened berries work just as well once thawed; include all their juice in the blender. Freeze-dried strawberry powder (2 tbsp) can boost flavor in the frosting.

Egg whites

Two whole eggs plus one white can replace the four whites. The crumb turns a more peach-tinted color and slightly richer.

Variations

Strawberry sheet cake

Bake the batter in a 23 x 33 cm (9 x 13 in) pan for 30 to 35 minutes and frost only the top.

Strawberry cupcakes

Fill 24 lined cups two-thirds full and bake for 18 to 21 minutes. The buttercream covers 24 with a modest swirl.

Troubleshooting

Cake is dense or gummy in the middle

The reduction was not cooked down enough, so it added too much water. Reduce it to 180 ml next time and make sure the layers bake until the center springs back.

Color faded to beige after baking

Some browning is normal. Reduce the purée over moderate heat so it does not caramelize, and pull the cake as soon as it tests done to keep the crumb pale.

Frosting is runny

The reduction was warm or added too quickly. Chill the buttercream for 15 minutes, then rebeat; add up to 60 g more powdered sugar if it is still soft.

Storage

Because the buttercream contains fruit, refrigerate the frosted cake, covered, for up to 4 days. Let slices sit at room temperature for 30 minutes before eating so the butter softens. The reduction keeps refrigerated for 5 days.

Safety notes

Do not taste raw batter, which contains raw flour and egg whites. Contains wheat, egg and milk.