NectarineGinger Biscuit galettegluten free

Name: Nectarine&Ginger Biscuit galette(gluten free)
Ingredients: For the filling; 4 nectarines,ripe; 1/2 cup light brown sugar; 1 1/2 teaspoons fresh ginger,shredded; 1/4 teaspoon ground cinnamon; 3 tablespoons fresh orange juice; 1 teaspoon Amaretto; 1 pinch salt; 1 tablespoon butter,room temperature; For the biscuit dough; 2 cups brown rice flour; 2/3 cup arrowroot flour or cornstarch; 1/3 cup tapioca starch; 1 teaspoon xantham gum; 1/2 cup sugar; 1 egg; 1/4 cup banana,mashed; 1 teaspoon vanilla extract; 1 cup cold butter,cut into cubes; 4 teaspoons baking powder; 1 egg,beaten