Grease and flour an 8-inch round pan with rice flour and line the bottom with parchment paper.

In a large bowl, whisk together millet flour, sorghum flour, potato starch, cornstarch, tapioca starch, guar gum, salt, and sugar.

In a separate bowl, combine warm water, yeast, and a pinch of sugar. Let sit for 5 minutes until foamy.

Add olive oil to the yeast mixture and then pour the wet ingredients into the dry ingredients.

Mix until just blended.

Using an electric mixer, beat on high speed for 2 minutes.

Spoon the dough into the prepared pan.

Cover the pan and let the dough rise in a warm place for 40-60 minutes, or until doubled in size.

Preheat oven to 400°F (200°C) with a rack in the lower third of the oven.

Once the dough has doubled, drizzle olive oil over the top and brush evenly across the surface.

Sprinkle with rosemary and sea salt.

Bake for 20 minutes, or until lightly golden brown.

Cool in the pan for 15 minutes before slicing and serving.