Bring all the ingredients for pancake batter to room temperature.
Place peaches, honey, thyme leaves, and salt in a bowl. Mix until peaches are coated with honey and set aside.
Preheat oven to 425 F and place a 10 inch cast iron skillet in the oven to heat. Remove any racks above the skillet since the pancake will puff up quite high.
Blend ingredients for pancake in a blender or vigorously whisk together in a large bowl. Let the batter sit for 5 minutes.
Open the door to the oven and pull out the rack that has the cast iron skillet. Carefully place butter or coconut oil in the heated cast iron skillet.
Once the butter has melted swirl it around so that it coats the sides of the skillet. Don't forget to wear an oven mitt!
Quickly pour in the batter and bake the pancake for 20 min. Do not open the oven during this time.
Remove skillet from the oven with puffed Dutch baby pancake. Top with peaches, powdered sugar if desired. Serve warm.