Ingredients

• 60 ml warm water
• 1 tablespoon + 1 teaspoon (9 g) instant dry yeast
• 500 g sifted wheat cake flour
• 65 g sugar
• 1 and 3/4 teaspoons salt
• 5 large eggs
• 350 g unsalted butter, moderately chilled

Crème pâtissière

• 500 ml milk
• 1 and 1/2 teaspoons vanilla extract
• 100 g sugar
• 5 large egg yolks
• 3 tablespoons wheat flour
• 3 tablespoons cornstarch

And

• 60 ml rum
• 40 g raisins
• 70 g (1/2 cup) powdered sugar
• 1 beaten egg for egg wash

Preparation

1. The evening before baking the buns, prepare the raisins, make brioche yeast dough, and prepare crème pâtissière. Cover the raisins with rum, cover, and place in the refrigerator overnight.
2. Pour yeast into a cup of warm water, mix, and set aside for 10-15 minutes (by then the yeast should be foamy; if nothing happens, you should repeat with different yeast). Pour flour into a bowl, sugar, salt, and yeast with water, mix with a wooden spoon. Add 3 eggs and, using a hand mixer or wooden spoon or dough hook, mix the ingredients at low speed. Add another egg, increase the mixer speed slightly, and mix until the ingredients almost combine into one mass. Add another egg and continue mixing. The dough should be smooth and elastic, but should stick to the bottom and sides of the bowl.
3. Work the dough by hand for 10 minutes or with a mixer fitted with a dough hook. Cover with a towel and set aside to rise in a warm place for 1 and 1/2-2 hours. Add butter to the dough in batches, about 2 tablespoons at a time, and blend it with the dough, kneading by hand or with a mixer fitted with a hook at medium speed. Later add more butter in smaller intervals as it blends faster with the dough. Mix only until the butter blends with the dough.
4. Place the dough in a bowl, cover with film, and place in the refrigerator overnight. Prepare crème pâtissière. Pour milk into a pot and add half the sugar. Over medium heat, bring to a boil. In the meantime, beat egg yolks with the remaining sugar into a fluffy cream for about 5 minutes. Sift both types of flour over the yolks and mix into a uniform mass. Gradually add the hot milk to the beaten cream, constantly stirring. Pour into the pot and bring the cream to a boil over medium heat, stirring constantly. Cook stirring vigorously for 2 minutes. Pour into a bowl and mix with vanilla extract. Cover the cream with transparent film so it adheres to the cream. Cool and place in the refrigerator overnight.
5. The next day, drain the raisins from the rum. Keep the rum and carefully mix 1 tablespoon of it with powdered sugar, set aside. Remove the yeast dough from the refrigerator and roll it out on a lightly floured work surface into a 35 cm square cake, 1/2 cm thin. Trim the sides to get a reasonably precise square. Remove crème pâtissière from the refrigerator and spread it on the dough. Sprinkle with raisins. Roll the dough quite tightly into a roll, seal the seams, and cut crosswise into pieces 2 and 1/2 cm wide. Arrange on a baking sheet lined with parchment paper and brushed with butter, 5 cm apart. Gently flatten each spiral with your hand and brush with egg. Set aside to rise without covering for about 1-1 and 1/2 hours.
6. Preheat oven to 220°C. Brush the spirals with the remaining egg and place in the middle section of the oven. Bake for about 15 minutes until golden. Remove from oven and transfer to a metal rack to cool. Do not turn off the oven. When the buns cool, brush them with the rum and powdered sugar glaze. Place the buns back on the baking sheet and place in the oven for 1-2 minutes. Transfer to a metal rack. Serve warm or at room temperature.