For the crumble: In a small bowl, stir together the pecans, sugar, chocolate chips, gluten-free flour blend and cinnamon.
For the cake: Preheat the oven to 375 degrees F and grease a 9-inch springform pan or round cake pan. In a large bowl, whisk together the gluten-free flour blend, baking powder and salt.
In a small bowl, whisk together the eggs and sugar until smooth. Beat in the oil and vanilla. Stir the egg mixture into the flour mixture until combined. Transfer the batter to the prepared pan, top with the pear, cranberries and crumble mixture. Bake until a toothpick inserted in the center comes out clean, about 45 minutes. Let cool in the pan set on a wire rack.
Gluten-Free Flour Blend:
In a large bowl, whisk together the rice flour, tapioca flour, potato starch, xanthan gum and salt.