To activate the yeast, heat the milk to 100–110°F and pour it into a mixing bowl. Stir in the yeast and let it sit for 5–10 minutes until it becomes bubbly and foamy.

Next, add the sugar and egg to the milk-yeast mixture and whisk until well combined. Stir in the flour and salt, then begin kneading the dough by hand or with a dough hook for 3–5 minutes.

Incorporate the softened butter into the dough one tablespoon at a time, ensuring each addition is fully mixed in before adding more. Continue kneading for another 5 minutes until the dough is smooth, soft, and slightly tacky.

Transfer the dough to a greased bowl, cover it with a towel, and let it rise in a warm area for 1–2 hours, or until it has doubled in size.

Once risen, punch down the dough and divide it into 6 equal portions. Shape each portion into a ball and flatten them into 6-inch rounds. Place the rounds on a parchment-lined baking sheet, leaving space between each bun.

For the custard filling, beat the cream cheese until smooth. Add the vanilla and heavy cream, mixing for 1 minute. Gradually incorporate the powdered sugar until the mixture is fluffy, then transfer it to a piping bag.

Brush each dough round with the beaten egg. Use the back of a spoon to create a shallow indent in the center of each bun. Pipe a generous swirl of the custard filling into each indent.

Spoon a small amount of blueberry jam over the custard and top with a few fresh blueberries.

To make the crumble, mix the melted butter, flour, brown sugar, and cinnamon until the mixture is crumbly. Sprinkle this generously over the filled buns.

Preheat the oven to 375°F and bake the buns for 20–25 minutes, or until they are puffed, golden, and the custard is just set.

Allow the buns to cool for 10 minutes to let the custard set, then dust lightly with powdered sugar before serving.