Preheat the oven to 350°F and grease an 8x4-inch loaf pan with 1 tablespoon butter.

Add the yeast and granulated sugar to the bowl of a stand mixer. Slowly pour in the milk, making sure the yeast is moistened. Let sit for at least 15 minutes to "bloom" as you prepare the other ingredients.

Add the flours, arrowroot, xanthan gum, baking powder, and salt to a medium bowl. Whisk well to combine, then whisk in the chopped rosemary.

When the yeast has bloomed (is very foamy), add the honey, egg, and avocado oil. Use the paddle attachment to mix on medium low speed until combined.

Add the flour mixture and mix on low until combined. Stop the mixer and scrape down the bowl, then mix on medium speed for 1 minute.

Use a spatula to scrape down the sides of the bowl and form into a ball (dough should form easily) and turn the dough ball out onto a well-floured surface.

Sprinkle the top of the dough with additional gluten-free flour, flatten it into a rectangle, and use a knife to cut the dough into 8 equal pieces.

Use well-floured hands to roll each piece of dough into a ball (best results if you squish/flatten the dough in your hands first, then roll into a ball). Place the dough ball in the prepared baking pan and repeat with the remaining dough balls. Dust your hands with gluten-free flour, as needed, to keep them from getting sticky.

Place the dough to rise in a warm spot (I like mine to rise on top of my preheated oven) and cover loosely with plastic wrap or a clean kitchen towel. Let the rolls rise for 1 hour.

After rising, brush the tops of the rolls with 1 tablespoon melted butter. Bake for 20-24 minutes.

Brush with the remaining tablespoon of melted butter and sprinkle the tops with flaky sea salt and more chopped rosemary. Remove from the pan and serve hot or warm.

Store leftover rolls in an airtight container for up to two days or wrap them in plastic wrap and place in a freezer bag to freeze.