Ham and cheese buns

Ingredients:

Dough

• 0.5 cups whole milk
• 2 and 1/4 teaspoons active dry yeast (7g packet)
• 2 tablespoons of sugar
• 4 tbsp (60 g) butter, melted, plus extra for greasing the bowl and cling film
• 1 large yolk
• 2 and 3/4 cups of premium flour, plus extra for work
• 1 teaspoon coarse salt

Filling

• 4 tbsp (60 g) butter + extra 2 tbsp, room temperature, for the frying pan
• 1 medium leek, white and light green parts, chopped (about 1 cup)
• 2 tbsp. premium flour
• 0.5 cups dry white wine
• 0.5 tbsp. grated Gruyère cheese
• 100 g thin slices of ham, cut into 0.5 cm pieces (about 4 slices)

Preparation:

1. Dough: In a medium saucepan, heat the milk and 0.5 cups of water over low heat until the temperature reaches 37°C (but not exceeding 43°C). Remove the saucepan from the heat and stir in the yeast. Sprinkle a pinch of granulated sugar on top and set aside, without stirring, for about 5 minutes. Then whisk in the butter and egg yolk.
2. In a large bowl, whisk together the flour, remaining granulated sugar, and salt. Make a well in the center and pour the yeast mixture into it, stirring with a wooden spoon until you have a thick, slightly sticky dough. Turn the dough out onto a floured work surface and knead until soft and elastic, about 6 minutes. Form the dough into a ball.
3. Grease the inside of a bowl with butter. Place the dough ball in the bowl, turning it to coat it with butter. Cover the bowl with plastic wrap, draw a circle on the wrap the size of the dough ball, and time it. Let the dough rise in a warm place for about 1.5 hours, until it doubles in size.
4. Remove the dough from the bowl and knead it slightly to release excess air. Form the dough into a ball again and place it in the bowl. Lightly grease a large piece of plastic wrap with butter and place it on top of the dough. Wrap the entire bowl tightly in another piece of plastic wrap and refrigerate for 4 hours or overnight to let the dough rise.
5. Prepare the filling: In a medium skillet, melt the butter over medium heat. Add the leeks and cook, stirring frequently, until softened and lightly caramelized, about 5 minutes. Sprinkle the leeks with flour and cook, stirring constantly, until golden brown and toasted, about 1 minute. Then whisk in the wine and 1/4 cup water and let the mixture thicken, stirring constantly, for about 1 minute. Remove the skillet from the heat and stir in the cheese, 1/2 teaspoon salt, and a few grinds of pepper. Transfer the filling to a medium bowl and let cool completely. (The filling will firm up slightly, but if it's too warm, it will be difficult to shape the buns.)
6. Form the filled buns: Grease a 22 x 32 cm (9 x 13 in) baking pan with 2 tablespoons of softened butter. Turn the dough out onto a floured work surface and press it down. Roll it into a 25 x 45 cm (10 x 18 in) rectangle, making sure the long edge is facing you. Spread the cooled filling evenly over the dough, leaving about an inch (2.5 cm) from the edge opposite you. Sprinkle the ham over the filling. Starting with the side closest to you, roll the dough into a tight log. Lightly brush the empty edge of the dough with water and continue rolling to seal the log. Tuck the ends in slightly, and if the log appears thicker in some places, smooth it out with your hands.
7. Using a serrated knife, cut the roll into 4-cm (1.5-inch) buns, making 12 total. Place the buns cut-side down (except the outer pieces) in the prepared pan, spacing them 2.5 cm (1 inch) apart. Cover the buns with plastic wrap. Let them rise in a warm place until they double in size, leaving no gaps between them, for about 1.5 to 2 hours.
8. Position a rack in the center of the oven and preheat the oven to 350°F (175°C). Bake the buns until golden brown and springy when lightly pressed, 25-30 minutes. Cool in the pan for 10 minutes.