Preheat oven to 350°F and prepare a middle rack in the oven. Grease a 6-well donut pan with cooking spray.
Bring the apple cider to a boil in a small saucepan. Lower the heat to a rapid simmer for 15-20 minutes until you have ½ cup reduced apple cider remaining in the saucepan. Let cool for 10 minutes.
Combine 3 tablespoons of the reduced apple cider in a small bowl with the flaxseed meal and let sit for 10 minutes.
Combine the soy milk with the apple cider vinegar and let sit for 5 minutes. Melt the vegan butter and let cool for 5 minutes.
Sift the spelt flour,light brown sugar, baking soda, cinnamon, pink salt, nutmeg, and ginger, cardamom, and ground cloves, if using, in a medium bowl. Whisk to combine.
Whisk the remaining reduced apple cider with melted vegan butter, soy milk mixture, and vanilla extract in a small bowl. Stir in the flaxseed mixture and whisk to combine. Add wet ingredients to the dry ingredients and whisk until smooth. Do not overmix.
Spoon the batter evenly into the donut pan, or transfer the donut batter to a pastry bag and pipe evenly into each of the donut pan wells.
Bake for 10 minutes until the edges are golden brown, and the top of a donut springs back when gently pressed. Make the cinnamon sugar while the donuts bake. Cool the donuts for 2 minutes on a cooling rack, then transfer the donuts onto the cooling rack and top with cinnamon sugar below while the donuts are still warm.
Make the Cinnamon Sugar
In a small bowl or plate, combine the organic cane sugar and cinnamon. Melt the vegan butter in a small saucepan, if using.
If using butter, brush the melted vegan butter onto the top of each donut, and dip each donut into the cinnamon sugar mixture. After 5 - 10 minutes, dip each donut into the cinnamon sugar mixture again. Best enjoyed immediately.
Store at room temperature for two to three days in an airtight container in a single layer or parchment paper between the layers.
To freeze, wrap each donut in plastic wrap, place it inside a freezer ziplock bag or container, and freeze for up to two months. Defrost the donuts on the counter for an hour or two.
These donuts are best enjoyed fresh, but leftovers can be stored in an airtight container at room temperature for up to 2 days in a single layer or parchment paper between the layers. Avoid stacking them or they will stick together.