1 cup granulated sugar
4 1/2 teaspoons ground cinnamon, divided
3 1/2 cups all-purpose flour
2/3 cup light brown sugar, packed
2 teaspoons baking powder
1 teaspoon kosher salt
1/2 teaspoon baking soda
1/2 teaspoon ground nutmeg
6 tablespoons butter, melted and cooled
2 large eggs, lightly beaten
2 cups vegetable oil
Heat apple cider in a small saucepan over high heat. Bring to a boil; reduce heat and simmer, stirring occasionally, until reduced to 1 cup, about 15-20 minutes. Let cool completely. In a small bowl, combine sugar and 1 tablespoon cinnamon; set aside. In a large bowl, combine flour, brown sugar, baking powder, salt, baking soda, nutmeg and remaining 1 1/2 teaspoons cinnamon. In a large glass measuring cup or another bowl, whisk together butter, eggs and apple cider. Pour mixture over dry ingredients and stir using a rubber spatula just until moist; cover and place into the refrigerator until chilled, about 1 hour. Divide dough in half. Working on a lightly floured surface, roll dough into 1/2-inch thick rounds; cut out rounds with a 2 1/2-inch cutter. Heat vegetable oil in a large stockpot or Dutch oven over medium high heat until a deep-fry thermometer registers 375 degrees F. Working in batches, add donuts to the Dutch oven and cook until evenly golden and crispy, 1 minute per side. Transfer to a paper towel-lined plate for 30 seconds; then roll warm donuts in cinnamon sugar mixture to coat. Serve warm.