Preheat the oven to 400 degrees Fahrenheit and line a baking sheets with parchment paper.
In a measuring cup or bowl, add the milk and apple cider vinegar together, stirring to combine and allowing it to sit for 3-4 minutes until mixture has thickened.
In large bowl, add the flours, baking powder, baking soda, cinnamon, nutmeg, and salt, whisking them all together until combined.
Add the pieces (or cubed) of butter and using a pastry blender, blend butter into dry ingredients until the mixture becomes “peas-like” and crumbly.
Pour the cold acv-milk mixture and stir (working it together with one hand) until the dry ingredients are moistened and able to form into a ball. NOTE: If the ingredients feels a little too dry, add 1 tablespoon of cold milk at a time, until it’s moistened BUT not too wet!
Add the dough onto a lightly floured surface and gently pat (or roll using a rolling pin) into an 8-inch square (about 1-inch thick). Then use a bench scraper (or large knife) to cut the dough into 4 equal squares. Stack the squares atop each other and pat or roll into an 8-inch square again. Repeat this process about 2 more times (patting/rolling and stacking).
Using a biscuit cutter, press it into the dough (NO twisting), lift, and remove the circular biscuit shaped dough and place unto baking sheet. Repeat until all biscuits are cut out. NOTE: Be sure to space out the dough about 1-inch apart when on the baking sheet.
To make the vegan egg wash: add the milk + maple syrup together in a bowl, mixing until combined.
Brush the tops with the vegan 'egg' wash to ensure that the tops are golden brown.
Bake in the oven 15-18 minutes or until golden brown and everything looks crispy. Remove from oven and let cool until warm.