Add the milk, water, instant yeast, and sugar to a bowl. Using a spoon, gently stir the ingredients until combined. Cover the mixture and set it aside for 10 minutes until bubbles form.
Mix and combine the white rice flour, tapioca flour, brown rice flour, xanthan gum, baking powder, and salt in a separate bowl. Then, add the yeast mixture to the center. Using a standalone mixer, at medium-high speed, with the paddle attachment fitted, beat the ingredients until the dough is formed ( about 4-5 minutes). You can also use your hands to form the dough. Add the olive oil and incorporate it into the dough using the standalone mixer or your hand.
Transfer the dough to a greased bowl and cover it with plastic wrap followed by a damp kitchen towel. Let the dough rest and rise for an hour.
Add two tablespoons of olive oil to a baking tray or casserole. I used a 28 x 5 cm ( 11 x 2 inch) baking tray. Transfer the dough to the tray and gently spread it into the shape of the tray with your fingers. Cover the dough with a clean damp kitchen towel, and let the dough rise for another hour.
Using your fingers, create dimples into the dough and drizzle olive oil. Then, add the basil leaves and cherry tomatoes. Cover the dough again with a damp kitchen towel and let it rise for another 30 minutes.
While the dough rises, preheat the oven to 210°C (410°F). Bake, the gluten free focaccia for 20-23 minutes or until a thermometer inserted through the middle of the Focaccia, reads 93° C (200° F). As soon as you remove the Focaccia from the oven, brush it generously with olive oil to keep it moist.
Let the focaccia cool in the pan for 5 minutes before transferring it to a cooling rack to cool down to room temperature.