Nai wong bao: steamed buns with custard

Ingredients:

Custard

• 1/3 cup condensed milk with sugar
• 1/4 cup cornstarch
• 2 tbsp. bleached premium flour
• 2 tablespoons powdered sugar
• 1 tsp. dry custard mix
• 0.5 tsp dry milk
• 1/4 teaspoon coarse salt
• 2 large eggs
• 5 tablespoons chilled unsalted butter, cut into pieces

Steamed buns

• 1 teaspoon active dry yeast
• 1.5 cups bleached premium flour + extra for working with the dough
• 1/4 cup whole milk, room temperature, add more if needed
• 3 tablespoons powdered sugar
• 1.5 tsp baking powder
• 0.5 tsp coarse salt
• 1 tbsp unsalted butter at room temperature

Preparation:

1. Place 2 inches of water in a medium saucepan and bring to a simmer over medium-low heat.
2. Custard:
   
   In a medium bowl, whisk together the condensed milk, cornstarch, flour, powdered sugar, creaming mix, dry milk powder, salt, and eggs until smooth. Strain through a fine-mesh sieve into a medium metal bowl.
3. Place the bowl over simmering water and heat in a double boiler, stirring constantly with a spatula and occasionally lifting the bowl from the pan if the custard starts to stick to the sides. Whisk until the mixture is thick but fluffy and smooth, about 7 minutes. The custard may curdle slightly, but continue whisking until it becomes smooth. Stir in the butter.
4. Transfer the custard to a clean medium bowl. Place a piece of plastic wrap directly on the surface of the custard and let it cool in the refrigerator for at least 2 hours or overnight.
5. Dough:
   
   In the bowl of a stand mixer, combine the yeast with 1/4 cup warm water (about 104°F/40°C) until the yeast is slightly dissolved. Let stand until the surface of the water begins to bubble, about 10 minutes.
   
   Note
   
   Active dry yeast should be dissolved in warm water. If the water is too hot or too cold, the yeast will not activate. Foam should appear on the surface of the water..
6. Add the flour, milk, powdered sugar, baking powder, and salt to the yeast mixture. Mix on low speed with the dough hook attachment until the dough begins to come together. If the dough looks dry, add whole milk 1 tablespoon at a time until the dough is smooth and no longer sticks to the sides of the bowl. Knead the dough on medium-low speed for about 8 minutes. Add the butter and mix again until smooth. Cover the bowl with a dry kitchen towel and let the dough rise in a warm place until it doubles in size, 1.5 to 2 hours.
   
   Note
   
   Proofing time may vary depending on room temperature and humidity. First, estimate the dough's volume (doubling or tripling)..
7. Meanwhile, cut 12 10cm squares from parchment paper and set aside.
8. Scoop 1 tablespoon of the set cream into balls and carefully roll them into balls. You should have 12 balls. Cover with plastic wrap and refrigerate until ready to assemble.
9. Place the bowl with the dough over the mixer and knead with the dough hook until the dough begins to deflate, about 1 minute. Transfer the dough to a lightly floured work surface and divide it into 12 pieces (about 30 g each). Cover the dough with a damp towel. Working with one piece of dough at a time, roll it into a 10 cm (4 in) circle, making sure the edges are thinner than the center. Place a ball of custard in the center of the circle and seal the custard with the dough. Place it on a piece of parchment paper and set aside. Repeat with the remaining dough and custard.
10. Place the steamer basket in the steamer and add enough hot water to almost reach the basket but not touch it. Place as many buns as will fit (straight on pieces of parchment) in the steamer basket, spacing them about 2 cm apart. Cover and let them sit over the hot water until the buns are puffy and glossy, about 30 minutes. Leave the remaining buns to rise, uncovered, on the counter.
11. Once the buns have risen, reduce the heat to medium and cook for exactly 12 minutes; set a timer. Turn off the heat and let the buns steam for 5 minutes. Open the steamer and enjoy the bao buns while they're still hot.
12. Immediately steam the remaining buns over medium heat for 12 minutes, then turn off the heat and let sit for 5 minutes.
    
    

    Freezing Tips

    
    Place the cooled bao on a baking sheet in a single layer, then transfer to a freezer bag and store in the freezer for up to 3 months. Reheat the frozen buns with steam for about 8 minutes. Let cool for 5 minutes and serve warm.