Place the warm milk in a large bowl. Sprinkle the yeast over the milk and let it stand until softened and foamy, 5 min.
Add the water and sugar to the milk and yeast. Mix to combine.
Add the flour and salt, mixing until a soft dough comes together. Turn the dough out on a lightly floured surface and knead for 5-7 minutes by hand (or 2-3 minutes in a stand mixer fitted with a dough hook), until the dough is smooth but still slightly sticky.
Shape the dough into a ball and place it into a clean bowl. Cover the bowl with a damp tea towel and let the dough rise in a warm and draft-free place until doubled, roughly 1 hour.
Once the dough has risen, punch it down. Re-cover it with the damp tea towel and let rise a second time, until doubled, roughly 1 hour.
Punch down the dough a second time and divide it into 6 portions. Shape each portion into a ball. Place the balls onto a lightly floured surface, cover them with the damp tea towel, and let them rest for 5-10 minutes.
After resting, flatten the balls into discs that are ½ inch thick. Place the flattened rounds on to a floured baking sheet. Cover them with the damp tea towel and let them rise for 20 minutes.
While the bread is rising this final time, preheat your oven to 450⁰F.
Once risen, uncover the dough, place the baking sheet into oven, and bake for 5-7 minutes, until the breads are just starting to turn golden.
Lower the heat to 300⁰F and bake for another 7-10 minutes, until evenly golden.
Remove the lepinja from oven and wrap them in a (dry) tea towel for 10 minutes to soften the crust.
Slice the lepinja open to serve, if desired. Serve warm.