In a large mixing bowl, combine 1 cup sourdough discard, 2 large eggs, ¼ cup melted butter, ½ tsp vanilla extract, and ¼ cup granulated sugar. Whisk until smooth and fully incorporated.

In a separate bowl, mix together 1 ½ cups all-purpose flour, 1 tsp baking powder, ½ tsp baking soda, ¼ tsp salt, ½ tsp ground cinnamon, and ¼ tsp ground nutmeg.

Gradually add the dry mixture into the wet mixture, stirring just until a soft, slightly sticky dough forms. Avoid overmixing to keep the doughnuts tender.

Wrap the dough in plastic wrap and chill in the refrigerator for about 30 minutes. This helps with easier handling and shaping.

Roll the chilled dough on a lightly floured surface to about ½ inch thickness. Use a doughnut cutter or two round cutters to shape the dough into rings. Gather and reroll scraps as needed.

If frying, heat oil in a deep pan to 350°F. Carefully lower a few doughnuts at a time into the oil and fry until golden brown, about 1 to 2 minutes per side. If baking, preheat the oven to 375°F and bake shaped doughnuts in a greased doughnut pan for 10 to 12 minutes.

While still warm, toss the cooked doughnuts in a mixture of ½ cup granulated sugar and 1 tbsp ground cinnamon until well coated.