Make the Fruit Reduction: In a small saucepan, combine jam, water, and strawberries. Simmer over medium heat, gently mashing the strawberries. Reduce until thickened, about 12–15 minutes. Cool completely before using.
Prep the Pans: Preheat oven to 350°F (177°C). Grease a 10-inch round springform cake pan.
Dry Ingredients: In a medium bowl, whisk together the cake flour, baking powder, baking soda, and salt.
Cream Butter & Sugar: In a large bowl, whisk the softened butter and granulated sugar until pale and fluffy, about 3-5 minutes.
Add Eggs: Beat in the egg whites until light and fluffy (medium peaks) and whole eggs until well combined and silky.
Add Labneh & Vanilla: Mix in the labneh (or yogurt) and vanilla paste until smooth and emulsified.
Alternate Dry & Milk: Add the dry ingredients, crushed freeze-dried berries, and milk. Mix until just combined—don't overmix.
Fold in the Flavor: Gently fold in the cooled strawberry-raspberry purée. The color will be soft pink and naturally tinted. pour into the cake mold.
Bake: Bake for 55-60 minutes, or until a toothpick inserted in the center comes out clean. Let cool in pans for 10 minutes, then transfer to wire racks to cool completely.
To Serve: Once cool, top with whipped cream and a few spoonfuls of extra strawberry-raspberry jam or purée. Garnish with fresh berries just before serving.
