Preheat oven to 400 degrees. Line muffin tin with baking cups. This recipe makes 6 muffins.
In a large bowl, combine rice flours, arrowroot, baking powder, xanthum gum, salt, pumpkin spice, and sugar. Whisk together.
In a second small bowl, whisk egg until frothy. Add olive oil and vanilla and whisk together. Pour into dry ingredients. Add pumpkin puree. Fold together with a spatula until all dry ingredients are incorporated, 15-20 strokes.
Combine all the streusel ingredients.
Scoop batter into prepared muffin cups, filling 1/2 full. Sprinkle with streusel topping and nuts. Add more batter to each cup, filling to the top. Again sprinkle with streusel and nuts.
Place in preheated oven. Bake for about 2 minutes, then reduce heat to 375. Bake additional 25 minutes or until tops spring back when gently pressed.