Herb Butter for Croissant Dough

Arrange herbs in a single layer on a microwavable plate lined with paper towels. Microwave on high until herbs are crisp and dried, 3 to 4 minutes, checking at 30-second intervals after 1 minute. Remove leaves from stems; discard stems.

Finely grind dried herbs with salt in a mortar and pestle. Combine herb mixture and butter in bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed until just combined, 30 seconds to 1 minute. Place butter between 2 sheets of parchment paper, and shape into a 7 1/2-inch square block of even thickness. Refrigerate until firm, about 45 minutes. Proceed with step 3 of All-Butter Croissant Dough.