In a large mixing bowl, whisk together 4 cups of all-purpose flour, 1/4 cup of granulated sugar, 1 teaspoon of salt, and 1 packet of active dry yeast until evenly blended.

In a small saucepan, melt 1/2 cup of unsalted butter, then stir in 1 cup of milk until well-combined.

Once combined, transfer the dough mixture onto a lightly floured surface. Knead the dough for about 5-7 minutes until it becomes smooth and elastic.

Shape the kneaded dough into a ball and place it in a greased bowl, covering it with a kitchen towel. Allow the dough to rise in a warm place for about 1 hour.

While the dough is rising, prepare the custard. Heat 1 cup of milk and 1/4 cup of sugar over medium heat. Whisk together 2 egg yolks, 2 tablespoons of cornstarch, and 1 teaspoon of vanilla extract before slowly adding this mixture to the hot milk.

After the dough has risen, punch it down gently and divide it into equal portions, typically about 12. Roll each piece into a ball, flatten it out, and then add a generous dollop of cooled custard and 1 teaspoon of raspberry jam in the center.

Preheat your oven to 200°C (400°F) while you arrange the shaped buns on a parchment-lined baking sheet.

Once the buns have risen, place them in the preheated oven and bake for 15-18 minutes.

Remove the danish buns from the oven and let them cool slightly on a wire rack. Mix powdered sugar with a tiny splash of milk to create a glaze and drizzle it over the warm buns.