In a small saucepan, whisk together 1/6 cup of the flour with the water over medium heat, stirring constantly until the mixture reaches 65°C (149°F) and becomes a thick paste—this takes about 5 minutes. This tangzhong technique creates a more tender, moist crumb by pre-gelatinizing some of the flour. Remove from heat and let cool slightly, then stir in the milk and honey until smooth. Once the mixture cools to 45°C (113°F), whisk in the 2 room temperature eggs and vanilla extract. Set this wet mixture aside.

In a large bowl, whisk together the remaining 3 2/3 cups flour, instant yeast, and 1/2 teaspoon of the salt (we'll add the remaining salt later for better gluten development). Pour the wet ingredient mixture from Step 1 into the dry ingredients and stir with a wooden spoon or dough hook until all flour is incorporated and a shaggy dough forms. This initial mixing hydrates the flour evenly.

Knead the dough by hand or with a stand mixer on medium speed for 3-4 minutes until it becomes smooth and elastic, then gradually add the softened butter cubes one at a time, allowing each piece to fully incorporate before adding the next. This takes about 6-8 minutes total. Once all butter is incorporated, add the remaining 0.75 teaspoon salt and continue kneading for another 1-2 minutes until the dough is silky, smooth, and springs back when poked—this indicates proper gluten development. The dough should be slightly tacky but not sticky.

Place the dough in a lightly oiled bowl, cover with plastic wrap, and let it rise at room temperature for 40 minutes until it increases by about 50 percent. Then punch down the dough gently to release excess gas, cover again, and refrigerate for at least 2 hours (or up to overnight)—this cold fermentation develops flavor and makes the dough easier to shape. I find that overnight chilling gives these buns an incredible depth of flavor that you simply can't rush.

Remove the dough from the fridge and divide it into two equal parts. Working with one portion at a time on a lightly floured surface, roll it into a 12x8 inch rectangle. Fold the dough into thirds like a letter (fold one short end to the middle, then fold the other short end over it), give it a quarter turn, and roll it out again to a 12x8 inch rectangle. Repeat this folding and rolling process one more time—this lamination creates beautiful layers. On the final roll, spread 1/3 cup of Nutella evenly over the dough, then roll it up tightly from the long side into a log. Repeat this process with the second portion of dough.

Cut each log into 1-inch thick slices and place them cut-side up in a greased muffin tin or on a parchment-lined baking sheet, spacing them about 1 inch apart. Cover loosely with plastic wrap and let them rise at room temperature for 45 minutes to 1 hour until they're puffy and nearly doubled in size. Meanwhile, preheat your oven to 180°C (350°F). Once proofed, brush the tops generously with the beaten egg, then bake for 22-25 minutes until golden brown and cooked through. The buns should spring back when lightly pressed. I always rotate my pan halfway through baking to ensure even browning.

Let the buns cool in the tin for 5-10 minutes, then transfer them to a wire rack to cool completely for about 20 minutes. Once cooled, transfer the melted white chocolate to a piping bag fitted with a small round tip and pipe crosses on top of each bun in a thin, even line. Let the chocolate set at room temperature for about 10 minutes before serving.