In a medium bowl, whisk together the gluten-free all-purpose flour, almond flour, baking powder, and salt. Set aside.
In a large bowl, beat the oil, brown sugar, granulated sugar, eggs, milk, orange zest, and vanilla extract.
Add the sifted dry ingredients and the peaches and mix until well incorporated. At this moment, you can also add chopped toasted walnuts.
Pour the mixture into the previously prepared pans. Fill the muffin cups ¾ full, dividing the mixture as evenly as possible. Sprinkle with the crumble.
Bake for 20 minutes or until cooked. Keep in mind that all ovens are different. To know if it's ready, insert a toothpick into the center of the muffins; it should come out clean, with no streaks of batter.
Let cool before removing.