How to Make It
In a large bowl combine 2½ cups flour, sugar, yeast, and salt. In a small pan, combine the yogurt, milk, and butter over medium-low heat until warm (about 100-110° F). Mix the wet ingredients into the dry ingredients until thoroughly combined. Add ¾ cup flour and eggs and mix until thoroughly combined. If necessary, add remaining flour, a little at a time, if dough is too sticky.
Transfer the dough to a floured surface and knead until smooth and supple, about 8 minutes. Transfer the dough to an oiled bowl and drizzle lightly with olive oil to coat. Cover loosely with plastic wrap and let rise in a warm place until doubled in size.
Meanwhile, make the herb butter: In a small bowl, stir together the softened butter, herbs, and lemon zest. Season with salt and pepper.
Punch dough down and transfer half to a lightly floured surface. Cover the remaining dough and place it in the refrigerator. Line a 6-quart slow cooker with parchment paper and oil the parchment. Divide the dough into 9 portions and roll into balls. Transfer balls to the prepared slow cooker. Cover and let rise 30 minutes.
Set the slow cooker to high and cook rolls until set, about 1 hour. (Note: the rolls will not be brown on top.) While the rolls are cooking, remove the second half of the dough from the refrigerator, roll it into 9 balls, and let rise on a sheet of oiled parchment.
Prepare the broiler. Remove the rolls from the slow cooker, transfer them to a baking sheet, brush them with herb butter and broil until golden brown, 2 to 3 minutes. Transfer the second batch of rolls to the slow cooker and repeat the process.