01 -
Combine lukewarm milk (30-35°C/85-95°F), water, yeast, and sugar in a bowl. Stir and set aside for 10 minutes until foamy.
02 -
In a stand mixer bowl with dough hook, combine flour, eggs, egg yolk, rum (if using), salt, and the yeast mixture. Knead on medium speed for 6-8 minutes until smooth and elastic. Add butter and knead for another 3-4 minutes until incorporated and the dough easily separates from the bowl.
03 -
Cover the bowl with clingfilm and let the dough rise at room temperature (20-25°C/68-77°F) for about 1-1½ hours until visibly increased in size.
04 -
Lightly flour a large baking sheet. Roll the dough into a 2 cm (0.8 inch) thick rectangle. Using an 8 cm (3-inch) heart-shaped cookie cutter, cut about 16 hearts. Shape leftover dough into balls. Place on the prepared sheet with space between them.
05 -
Cover doughnuts with a lightly dampened kitchen towel and let rise at room temperature for 1-1½ hours until they triple in size.
06 -
Heat oil in a large pan to 170-180°C (340-355°F). Carefully place doughnuts seam-side up into the oil, about 4-5 at a time. Cover with lid and fry for 2-3 minutes, then uncover, flip, and fry another 2-3 minutes until golden. Transfer to a paper towel-lined rack.
07 -
Mix all sugars in a deep plate. Coat warm doughnuts in the sugar mixture. For jam filling, warm it slightly in a saucepan. Transfer your chosen filling to a pastry bag and pipe into the doughnuts. Serve immediately.