In a small bowl, mix together apple cider vinegar and almond milk. Let sit for 5 minutes. In a large bowl, whisk together flour, baking powder, salt, rosemary.
Cut in the cold vegan butter to the flour mixture with two forks until the vegan butter is the size of small peas (some can be larger). Carefully stir in the almond milk mixture.
Spoon the dough out on a cold surface sprinkled with gluten-free flour. With your hands, carefully pat the dough into a 1 inch square. Using a circle biscuit cutter or a drinking glass, cut out your biscuits.
Place biscuits on a baking sheet lined with parchment paper. Brush tops of biscuits with melted vegan butter. Bake for 10-15 minutes, until lightly browned.