Preheat oven to 350°F (180°C). Spray donut pan with non-stick spray. Set aside.
Make the donuts: In a medium bowl, whisk together the milk, butter, Domino® Golden Sugar, egg, sour cream, and vanilla bean paste until well combined. Set aside.
In a large bowl, whisk the flour, baking powder, baking soda, cinnamon, and salt together. Pour the wet ingredients into the dry ingredients, and mix until just combined. The batter will be slightly thick.
Spoon the batter into a large ziplock bag or pastry bag and pipe it into the donut cavities, filling about halfway.
Bake for 9-10 minutes or until the edges and tops are lightly browned. To test, poke your finger into the top of the donut. If the donut bounces back, they’re done. Cool donuts for 2 minutes then transfer to a wire rack. Re-grease the pan and bake the remaining donut batter.
Coat the donuts: Combine the Domino® Golden Sugar, cinnamon, ginger, cardamom, allspice, and pepper together in a medium bowl. Once cool enough to handle, lightly brush the donuts with melted butter, then toss generously in the chai-spice sugar.
Donuts are best served immediately. Leftovers keep well covered tightly at room temperature for up to 1 days.