Top down view of blackberry tray bake squares on wooden board with black spatula with blackberries and prunes, tray bake tin and blackberries in white dish in background.

Blackberry Tray Bake with Prunes (Healthy)

This Polish inspired easy Blackberry Tray Bake with Prunes is low in fat and sugar, perfect as a light, deliciously fruity treat or snack.
Course Dessert, Snack
Cuisine Polish
Keyword blackberry, cake, prunes
Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings 9 squares
Author Monika Dabrowski


  • 300 g blackberries
  • 200 g prunes pitted, finely chopped
  • 2 eggs at room temperature, yolks and whites separated
  • 100 g caster sugar plus 2 tablespoons and 1 teaspoon
  • 100 g butter at room temperature (plus a little more for greasing the baking dish)
  • 3 tablespoons fromage frais
  • 230 g self-raising flour
  • ½ teaspoon baking powder
  • 1 teaspoon vanilla extract
  • 1 tablespoon cocoa powder or cacao, it's better for you
  • Demerara sugar and almond flakes to sprinkle on top


  • In a saucepan combine the blackberries, prunes and 2 tablespoons of sugar, stir and cook over a low/medium heat for approximately 6 minutes, stirring often and squashing the fruit with the back of the spoon as you stir. The mixture will be thick and sticky. Set aside to cool completely.
  • Preheat the oven to 365 F/ 190 C/ gas mark 5. Grease a 23 cm square (or equivalent) baking dish and line with parchment paper (alternatively, instead of using paper, grease the tin lightly, sprinkle with a little flour and shake to spread it evenly around the sides and bottom). Set aside.
  • Sift together the flour and baking powder. Set aside.
  • Beat the butter, 100g of sugar, egg yolks, vanilla extract and fromage frais until smooth and lighter in colour (about 3 minutes). Start gradually adding the flour mixture. When the dough begins to form place it on a work surface and knead in any remaining flour. Do NOT knead for too long, only until all the ingredients have been incorporated.
  • Divide the dough into 2 parts (1 larger - two thirds, and 1 smaller - one third). Flatten the larger dough with your hands and place in the baking dish - continue flattening until it covers the bottom evenly and completely (you may want to dust your hands with a little flour to prevent the dough from sticking to them).
  • Cover with the fruit mixture, using the back of the spoon to even it out.
  • Whisk together the egg whites with 1 teaspoon of sugar until light and fluffy (about 1.5-2 minutes using an electric mixer). Spread over the top of the fruit mixture, using the back of the spoon to even it out gently - do NOT press down.
  • Sprinkle the cacao (or cocoa) powder on the smaller dough ball and knead until all the powder has been absorbed. Coarsely grate the dough over the top of the cake - do NOT press down!
  • Sprinkle some Demerara sugar and almond flakes over the top (1-2 tablespoons each) and bake for 35 minutes. Remove from the oven, allow to cool for a few minutes and serve!


Serving: 0g | Carbohydrates: 0g | Protein: 0g | Fat: 0g | Saturated Fat: 0g | Polyunsaturated Fat: 0g | Monounsaturated Fat: 0g | Trans Fat: 0g | Cholesterol: 0mg | Sodium: 0mg | Potassium: 0mg | Fiber: 0g | Sugar: 0g | Vitamin A: 0IU | Vitamin C: 0mg | Calcium: 0mg | Iron: 0mg