Preheat oven to 375 degrees F. Line a baking sheet with parchment paper and set aside.

Add whole milk and white vinegar to a small bowl, and stir to combine. Allow the mixture to sit for 5 minutes while preparing the next steps.

In a large mixing bowl, add gluten-free flour, xanthan gum (if required), baking powder, baking soda and salt. Whisk to combine.

Slice the stick of butter down the center lengthwise, then cut into chunks.

Cut the butter into the flour mixture using a pastry cutter.

Add the milk mixture, whisked egg and honey to the mixing bowl. Stir until incorporated.

Using clean hands, work the dough into a ball.

Place the dough ball onto the prepared baking sheet. Cut an X in the top center of the loaf.

Brush melted butter over the surface of the dough ball.

Bake in preheated oven for 45-55 minutes or until golden brown. Allow the bread to cool completely before slicing and serving.