In the bowl of a stand mixer fitted with the dough hook attachment, combine all of the dough ingredients and knead on medium low speed for about 5 minutes. The dough should come together in a cohesive ball that pulls away from the sides of the bowl but is still slightly sticky. If the dough does not come together, add in more flour 1 tablespoon at a time until the dough pulls away from the sides of the bowl.
Place the dough in a large, lightly greased bowl and cover. Place the dough in the fridge and chill overnight (8-12 hours).
In the morning, remove the dough from the fridge and allow it to rise at room temperature for about 30 minutes.
When the dough is finished rising, lightly punch it down and then turn it out onto a lightly floured surface. Roll the dough into a large rectangle about ½ inch thick.
Using a 3 ½ inch round cookie cutter, cut the dough into 12 circles. If you don't quite get 12 you can re-roll the scraps and cut out more circles. If desired, you can then use the leftover scraps to make donut holes! Use a 1 inch or 1 ½ inch round cookie cutter to punch some donut holes out of the scraps. Lightly cover the donuts and let rest while the oil is heating.
Lightly cover the donuts and let rest while the oil is heating.
Pour 2-4 cups of vegetable oil (you want it to be about 2 inches deep) into a large, heavy bottomed pot or dutch oven and heat over medium high heat until the oil reached 375°F. Place a cooling rack on top of a baking sheet and position it next to your stove. [I love this thermometer because it clips to the pot.]
Once the oil reaches 375°F, fry 3-4 donuts at a time for 1 minute on each side. The donuts should be a deep golden brown. Remove from the oil and place on the cooling rack to allow excess oil to drain off. I always make 1 donut first and check to make sure it's cooked through!
Repeat with the remaining donuts as well as the donut holes.
Add about ½ cup granulated sugar to a small bowl.
While the donuts are still warm, toss them in the granulated sugar! Place back on the cooling rack and allow to mostly cool to room temperature before filling.
Nutella Cream Filling
In a large bowl using a handheld or stand mixer fitted with a paddle attachment, cream together the softened butter and Nutella until smooth.
Add in the powdered sugar and salt and mix on low until fully combined.
Then beat on high for 3-5 minutes until the buttercream is super light and airy.
If the frosting in too thick, you can add in 1 tablespoon of cream at a time to thin it out a bit.
Transfer the Nutella buttercream filling to a piping bag fitted with a large bismark tip. Poke the bismark tip into the side of each donut and fill with the Nutella frosting. [It's easiest to make a hole in the side of the donut using a chopstick prior to filling.]
These Nutella donuts are best eaten immediately!
Notes
Please note that this recipe was specifically designed for deep frying the donuts. If you would prefer baked donuts, I suggest looking up a different recipe.These donuts are best eaten the same day, but will keep covered in the fridge for up to 2 days.