Ingredients
1 (432g) package white cake mix (such as Pillsbury®)
85g white cake mix extender
300ml water
4 egg whites
80ml vegetable oil
225g sliced fresh strawberries, pureed
283g jar strawberry preserves
15g confectioners' sugar
5ml lemon juice
Directions
Step 1
Preheat the oven to 175 degrees C (350 degrees F). Grease and lightly flour a 23x33cm baking pan.
Step 2
In a large bowl, use an electric mixer to blend together cake mix plus extender, water, egg whites, and oil until just combined. Pour the batter into the prepared pan.
Step 3
Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, for 26 to 32 minutes.
Step 4
Meanwhile, in a medium bowl, combine the pureed strawberries and strawberry preserves. Stir in confectioners' sugar and lemon juice until well mixed. Refrigerate the sauce until ready to use.
Step 5
Transfer the cake to a wire rack and let it cool to room temperature, for at least 25 minutes.
Step 6
Using the handle of a wooden spoon, poke holes into the cake about 2.5cm apart. Slowly spread the sauce over the cake, allowing it to fill the holes. Refrigerate until completely chilled.