Preheat the oven to 350F and spray a 9x5-inch loaf pan with gluten-free nonstick cooking spray, then line with parchment paper.
In a large bowl, whisk together the flour, xanthan gum, granulated sugar, baking powder, baking soda, salt, and cinnamon. Set aside.
In a medium bowl, whisk together the eggs, brown sugar, milk, oil, and vanilla.
Pour the wet ingredients into the dry ingredients. Mix until just combined, then gently fold in the diced peaches. Transfer the batter to the prepared baking pan, spreading it evenly in the pan.
Bake for 50-60 minutes or until a cake tester or toothpick comes out clean. Cool in the pan for 20 minutes, then remove the bread from the pan using the parchment paper, discard the parchment paper, and let the bread cool completely on a wire rack.
When the bread is cool, mix the glaze ingredients in a small bowl until smooth. Add more milk, a teaspoon at a time, if needed.
Pour the glaze over the bread and let it set for 15-30 minutes before slicing and serving.
Notes
Note: Fresh or canned peaches can be used. If using canned peaches, drain well.