In a large bowl, whisk together the milk, butter, banana and egg. Then add in the Gluten-Free Pancake Mix and rest the batter for 5 to 10 minutes.
Preheat the griddle to medium heat. Preheat the oven to low heat.
Meanwhile, pour the sugar over the strawberries and stir to combine, then set aside. Lightly grease the griddle and scoop 1/4-cup portions of the batter onto the griddle. Cook until bubbles form on the top of the pancakes and the edges appear dry, 3 to 4 minutes, checking after 2 minutes to make sure they aren't too brown. Adjust the heat as needed. Flip the pancakes and cook until the other side is brown and the pancakes feel firm when lightly pressed with a spatula, 1 to 3 minutes. Place the finished pancakes in the warm oven, and repeat for the remaining batter, 8 to 10 pancakes total.
Stack three pancakes with strawberries between each layer and top with syrup to serve.
Gluten-Free Pancake Mix:
In a large bowl whisk together the rice flour, buckwheat flour, oat flour, sugar, baking powder, baking soda, salt and xanthan gum. Store in an airtight container until ready to use.