In a stand mixer, combine 4 cups of all-purpose flour, 1/4 cup of sugar, 1 teaspoon of salt, and 10 grams of fresh yeast. Add 4 large eggs and knead the mixture on medium speed for about 10 minutes until it becomes a smooth dough.

Once your dough has reached the right consistency, shape it into a ball and place it in a lightly greased bowl. Cover the bowl with plastic wrap or a damp cloth, and let the dough rise in a warm spot for approximately 2 hours, or until it has doubled in size.

In a saucepan, gently heat 2 cups of whole milk and 2 tablespoons of unsalted butter along with the split vanilla pod over medium-low heat. In a separate bowl, whisk together 4 egg yolks, 1/4 cup of sugar, and 2 tablespoons of cornstarch. Gradually add the warm milk mixture to the egg mixture, stirring constantly. Return the mixture to the saucepan and cook over low heat, stirring until it thickens—about 5 minutes.

After the dough has risen, punch it down and roll it out into a rectangle about 1/2-inch thick on a lightly floured surface. Spread the chilled custard evenly over the dough, then sprinkle with mini chocolate chips. Roll the dough up tightly, fold it over, and cut it into 8 equal pieces. Arrange these pieces in a greased baking dish and let them rise again for another 2 hours, covered lightly with a cloth.

Preheat your oven to 350°F (180°C). Once the brioches have risen and appear puffy, prepare an egg wash by beating 1 egg and gently brushing the tops of each brioche. Bake them in the preheated oven for 10–12 minutes, or until they are beautifully golden brown.

While the brioches are baking, prepare a simple glaze by mixing 1/4 cup of boiling water with 2 tablespoons of sugar until dissolved. Once the brioches are out of the oven, brush the tops with the sugar syrup while they are still warm. Allow the finished brioches to cool on a wire rack before serving.