For the gluten-free flour blend: In a large bowl, whisk together the rice flour, tapioca flour, potato starch, xanthan gum and salt.
For the pancakes: In another large bowl, whisk together 1 cup of the gluten-free flour blend, almond flour, millet flour, baking powder and salt. (Reserve the remaining gluten-free flour blend for another use.)
In a medium bowl, whisk together the milk, eggs, oil, honey, vanilla extract and almond extract if using; stir into the flour mixture until combined.
Heat a large nonstick skillet or griddle and grease with butter. Scoop 1/4-cup mounds of batter into the skillet and spread to make 3-inch rounds. Cook over medium heat until the pancakes are golden on the bottom, about 2 minutes. Flip and cook until fluffy and cooked through, about 2 minutes more. Transfer the pancakes to plates and top with the almonds and maple syrup.