1. In a stand mixer fitted with the dough hook attachment, combine the warm milk, sugar, and dry active yeast. Use a whisk to combine, and let the mixture rest for 5 minutes at room temperature to activate the yeast.
  2. Add the eggs and vanilla extract to the bowl, and whisk to combine.
  3. With the mixer on low speed, slowly add the unbleached flour and salt to the bowl. Once the dry ingredients are added, a shaggy dough will start to come together. Drop in 1 tablespoon of Kerrygold Unsalted Butter at a time, kneading after each addition, until it is incorporated.
  4. Turn the mixer off, and loosely cover the bowl with a clean kitchen towel. Let the dough rest for 10 minutes at room temperature. Next, knead the dough on medium low speed for 8-10 minutes until the surface of the dough is smooth. Remove the dough hook, and cover the bowl with plastic wrap, and let the dough rise at room temperature for 1 hour. Then place the dough in the fridge for another 30 minutes.
  5. Meanwhile, make the homemade strawberry jam. In a medium saucepan, combine the chopped strawberries and sugar. Cook over medium heat for 10 minutes until the strawberries break down. Add the lemon juice and simmer over low heat until the mixture thickens to a jammy consistency and coats the back of a spoon, about 10-12 minutes. Stir often, to ensure that the bottom doesn’t burn. Remove the jam from the heat, and pour in the vanilla extract, stir to combine, and allow the jam to cool, then place the jam in a heat proof container, and refrigerate until ready to use.
  6. Dust your work surface with flour, and pour the brioche dough out onto the work surface.
  7. Cut 14 4×4 inch square pieces of parchment paper, set aside. Divide the dough into 14 equal pieces. Take each piece, pinch the corners under, then roll each piece into a round ball on the work surface. Set each piece of dough onto a square of parchment, and place the dough balls on a rimmed baking sheet. Repeat with the remaining pieces of dough. Cover the dough loosely with a clean kitchen towel, and let rise for another 30 minutes until puffy.
  8. Place the prepared jam into a piping bag with a round piping tip.
  9. Pour the cup of granulated sugar, ground nutmeg, and ground cinnamon into a shallow bowl. Stir to combine.
  10. Place a baking rack on top of a rimmed baking sheet. Set aside.
  11. Fill a large Dutch oven with 3 inches of peanut or sunflower oil. Heat the oil to 350 degrees F. Carefully lower the doughnuts, 2-3 at a time, into the oil and cook for 2 minutes on the first side, flip using a chopstick, and cook for another 2-3 minutes until golden brown. Use a spider tool to remove the fried doughnuts from the oil, and place on the baking rack. Repeat until all of the doughnuts are fried.
  12. Dip each doughnut into the cinnamon sugar mixture, coating both sides.
  13. Poke a hole into the side of the doughnuts, and fill with the homemade strawberry jam. Enjoy immediately.