In a medium bowl, whisk together lukewarm milk, one egg, and melted butter until the mixture is smooth and well combined.

In a separate large mixing bowl, thoroughly whisk together all-purpose flour, sugar, and instant yeast.

Gradually add the wet ingredients into the bowl of dry ingredients, stirring gently to incorporate until a slightly sticky dough forms.

Transfer the dough to a lightly oiled bowl, covering it with a clean kitchen towel. Place the bowl in a warm spot and allow it to rise for 1.5 to 2 hours.

Once the dough has risen, turn it out onto a generously floured surface and roll it out to about ¼ inch thickness.

With a round cutter, cut out donut shapes from the rolled dough and place them on parchment paper.

In a deep frying pan, heat oil to a temperature between 170-180°C (340-360°F).

Carefully fry the donuts in batches, cooking each for 2 to 3 minutes per side until golden brown.

While the donuts are cooling, beat the heavy cream and sugar in a chilled bowl until stiff peaks form.

Once the fried donuts have cooled slightly, carefully cut each donut in half horizontally and fill them with whipped cream.

To finish, dust the filled donuts with powdered sugar for a sweet touch and serve warm or at room temperature.