Step 1

To make the dough, in a small bowl or a 2-cup liquid measuring cup, whisk together the whole eggs and egg yolks, the melted butter, milk and lemon zest. In a stand mixer with the dough hook, mix the flour, white sugar, yeast and salt on low until combined, about 20 seconds. With the mixer running, gradually add the milk-egg mixture; mix, scraping the bowl once or twice, until a slightly lumpy dough forms, about 2 minutes. Increase to medium-high and mix until the dough is smooth, shiny and elastic and pulls away from the sides of the bowl, 8 to 10 minutes.

Step 2

Detach the bowl from the mixer and lift out the hook with dough clinging to it; the dough will be sticky and fall from the hook in a thick rope into the bowl. Using a silicone spatula, scrape the sides of the bowl and gather the dough in the center. Cover with plastic wrap and let rise at room temperature until just shy of doubled, about 45 minutes, then refrigerate for at least 8 hours or up to 24 hours.

Step 3

When you are ready to shape the dough, remove it from the refrigerator. Line a rimmed baking sheet with kitchen parchment. Dust the counter with flour and scrape the chilled dough out onto it. Divide into 12 portions, each about 70 grams (2½ ounces). Flour your hands, then form each piece into a taut ball by rolling it against an unfloured surface in a circular motion under a cupped hand. Place the balls seam down on the prepared baking sheet in 3 rows of 4, spaced 1½ to 2 inches apart. Mist a sheet of plastic wrap with cooking spray and drape it over the baking sheet, then cover loosely with a kitchen towel. Let rise until the balls have expanded slightly and hold an indentation when lightly pressed, 1 to 1½ hours.

Step 4

Meanwhile, make the cream cheese filling and crumb topping (if using). In a medium bowl, combine the cream cheese, powdered sugar and lemon zest and juice; mix with a silicone spatula until smooth. Cover and refrigerate until needed. In a small bowl, whisk the egg with 1 teaspoon water; set aside for brushing the shaped dough. To make the crumb topping, in a small bowl, stir together the flour and white sugar. Add the butter and toss, then use your fingers to rub it into the flour mixture until it is in pea-sized pieces; cover and refrigerate until needed. Heat the oven to 350°F with a rack in the middle position.

Step 5

Leaving the dough balls in place on the baking sheet, use your fingers to create a 2-inch-wide hollow in each that is about as deep as the ball itself; it’s fine if this causes the portions to touch. Brush the buns with the egg wash. Remove the cream cheese filling and jam from the refrigerator. Fill each hollow with 1 slightly mounded tablespoon cream cheese filling. Use the back of a small spoon to create an indentation in each portion of cream cheese filling, then spoon 2 teaspoons jam into each. If using crumb topping, sprinkle it onto the edges of the buns.

Step 6

Bake until the buns are golden brown and spring back when gently pressed, 20 to 22 minutes. Cool on the baking sheet on a wire rack for at least 10 minutes. Serve warm or at room temperature.