• Mix: To a stand mixer bowl, add the flour, sourdough starter, whole milk, egg, sugar, and salt. Mix on low speed for 3-4 minutes until everything is incorporated.
• Add Butter: Add the softened butter to the bowl.
• Knead The Dough: Increase the speed of your mixer and mix for 10 minutes until the dough comes together and pulls away from the sides. It should be smooth and elastic. If the dough does not come together, slowly add 25g more flour at a time until it forms a ball around the dough hook.
• Let The Dough Rise: In a lightly greased bowl, cover and let the dough rise for 4 - 6 hours. During that time, perform 2 -3 stretch and folds, starting at the 30 minute mark, and repeating every 30 minutes until 3 are complete. The dough is done when it’s roughly doubled in size.
• Cold Proof: Transfer dough to the fridge to cold proof overnight (8-12 hours).
• Shape Donuts: The next morning, remove your dough from the fridge. On a lightly floured surface, divide the dough into 12 equal pieces. Roll each piece into a ball and round a few times with the palms of your hands.
• Final Rise: Transfer your shaped donuts to a lined baking sheet. I like to cut individual squares of parchment paper so it’s easy to pick up and drop each donut into the oil later. Loosely cover the donuts and let them rise until they double in size and are very puffy (2-5 hours at room temperature). Tip: If your oven or countertop oven has a proof setting, can you proof at 90 degrees for 1-2 hours.
• Cook: Pour oil into a heavy-bottomed pot or dutch oven and heat to 375 degrees F (about 15 minutes). Once the oil is heated, carefully place the add the donuts to the oil, 2-3 at at a time, and cook for 1 minute on each side, until deep golden on both sides. Transfer cooked donuts to a prepared rack and leave to cool. Continue in batches until all donuts are cooked.
• Toss in Sugar: Pour the granulated sugar into a bowl or plate. Toss the donuts in sugar on all sides until evenly coated.
• Pipe: Use a chopstick or similar tool to poke a hole in the donuts, approximately ¾ of the way in. Gently round the chopstick to form a hole. Use a piping bag to pipe the homemade Nutella filling until it is poking out of the top.
• Serve and enjoy!

Make The Nutella Filling

• Roast: Line your raw hazelnuts on a baking sheet and roast at 400F for 6-8 minutes, until lightly toasted. Place the roasted hazelnuts on a kitchen towel and rub together to remove the skins.
• Blend: Pour the roasted, skinned hazelnuts into a food processor or strong blender and blend into a nut butter.
• Add Remaining Ingredients: Add the sugar, salt, vanilla extract, and coconut oil and blend until you have a smooth and creamy Nutella texture.