Combine warm water, sugar, and yeast in a 2 cup measuring cup or small bowl and let it sit for about 5 minutes until bubbly.
Whisk the egg and the remaining 3 Tablespoons Olive Oil into the yeast mixture.
In the bowl of a stand mixer fitted with paddle, mix flour, oat flour, psyllium husk, salt, and xanthan gum together on low speed until combined, about 1 minute.
Turn the mixer onto low and slowly add yeast mixture mixing until combined and scraping down the bowl as needed. This should bake about 1 minute.
Increase speed to medium and beat for 6 minutes until the dough is sticky and uniform, scraping down the bowl once during the mixing process. The dough will resemble cookie dough.
Using a rubber spatula, scrape the dough into the prepared pan.
Using wet hands, press dough gently and as evenly as possible into the pan to the corners and smoothing out the top.