Instructions

In bowl of stand mixer, whisk milk, sugar, egg and yolk, and yeast until sugar has dissolved, then let sit until foamy, about 5 minutes. Add flour, scallions, and salt. Fit mixer with dough hook and knead on medium-low speed until dough is shaggy, about 2 minutes.
With mixer running, add softened butter, 1 piece at a time. Knead until dough is smooth, about 5 minutes, scraping down dough hook and sides of bowl occasionally. Transfer dough to lightly floured counter and knead by hand to form smooth, round ball, about 30 seconds. Transfer dough seam side down to lightly greased large bowl; cover with plastic wrap; and let rise until doubled in size, 1½ to 2 hours.
Grease 12-cup muffin tin. Press down on dough to deflate. Transfer dough to lightly floured counter, divide in half, and cover loosely with greased plastic. Press and roll 1 piece of dough (keep remaining piece covered) into 15 by 12-inch rectangle, with long side parallel to edge of counter.
Using pizza wheel or sharp knife, cut dough vertically into 6 (2½-inch by 12-inch) strips. Combine 3 tablespoons melted butter and curry paste in small bowl. Brush tops of 5 strips evenly with half of butter–curry paste mixture, leaving 1 strip unbrushed. Sprinkle ¼ cup cilantro over brushed dough strips. Stack strips squarely on top of each other, brushed side to unbrushed side, finishing with unbrushed strip on top.
Using sharp knife, cut stacked dough strips crosswise into 6 equal stacks. Place stacks, cut side up, in muffin cups. Repeat with remaining dough, remaining butter–curry paste mixture, and remaining ¼ cup cilantro. Cover muffin tin loosely with greased plastic and let dough rise until doubled in size, 1½ to 2 hours.
Adjust oven rack to upper-middle position and heat oven to 350 degrees. Bake until golden brown, 20 to 25 minutes, rotating muffin tin halfway through baking. Let rolls cool in muffin tin for 5 minutes, brush with remaining 1 tablespoon melted butter, and serve warm.