Prepare the yeast starter. To the warm (make sure it’s not hot) milk, add 1 tbsp of plain flour, 1 tbsp of sugar, and the yeast. Mix thoroughly and set aside for 20 minutes in a warm place.

In the bowl of a stand mixer, add the plain flour, sugar, eggs, a pinch of salt, and the prepared yeast starter. Stir briefly with a spoon. After a moment, add the melted butter (make sure it’s not hot). Using the dough hook attachment, knead until the dough is smooth and elastic. It should be quite loose and may stick to your hands. It will firm up slightly after rising.

Place the kneaded dough into a large bowl dusted with flour. Set aside to rise for about 1.5 hours.

In the meantime, prepare the crumble topping. In a bowl, combine the flour, cold butter cut into pieces, and sugar. Mix with your hands until the mixture resembles coarse crumbs.

Thoroughly wash and dry the blueberries. Mix them with the sugar and set aside.

Preheat the oven to 180°C.

Place the risen dough on a floured surface and knead briefly (dust your hands with flour to prevent sticking). Then, divide the dough into 10 equal parts.

From each part, form a flat disc with your fingers. Place a portion of blueberries in the centre of each disc, then pinch the edges of the dough together to seal. Gently shape the filled dough into a bun with your hands.

Place the prepared buns on a baking tray lined with parchment paper. Brush each bun with the beaten egg and sprinkle with the crumble topping. Set aside to rise again for about 20 minutes.

Bake the risen buns for about 17-20 minutes. Check after 15 minutes, if they are too pale, continue baking, checking every few minutes. The buns should be lightly browned on top, and the crumble should be crispy. Enjoy!