Prepare the Wet Ingredients: In a large bowl, crack the egg and whisk lightly. Add the milk, condensed milk, sugar, salt, and instant dry yeast. Stir well until all the ingredients are fully combined.

Combine with Flour: Gradually add the strong flour to the mixture, stirring with a spatula until it begins to form a shaggy dough. Cover the bowl with plastic wrap and let it rest for about 30 minutes. This rest period allows the flour to hydrate and the yeast to start activating.

Knead the Dough: Add the softened unsalted butter to the dough. Knead the dough by hand for about 10-15 minutes, or until it becomes smooth and elastic. This step is crucial as it develops the gluten, giving the bread its light, airy texture.

First Proofing: Place the kneaded dough in a clean bowl, cover it with plastic wrap, and let it rise in a warm place for about 40 minutes, or until it doubles in size. The dough should be soft and puffy at this stage.

Add Condensed Milk: Add the condensed milk to the butter mixture and continue to mix until fully incorporated. The result should be a smooth, creamy spread that will add extra richness to the bread.

Divide and Rest the Dough: Punch down the risen dough to release excess gas. Divide the dough into three equal portions, about 200 g each. Shape each portion into a ball, cover them with plastic wrap, and let them rest for 15 minutes.

Roll and Fill: Using a rolling pin, roll each ball of dough into a long rectangle. Spread a thin layer of condensed milk cream over the dough, then roll it up tightly from one end to the other, forming a log.

Cut and Arrange: Cut each rolled log into six equal pieces and place them cut side up into the prepared molds. The pieces should be snug but not overly tight, as they will expand during the final proofing.

Final Proofing: Cover the molds with plastic wrap and let the dough rise for an additional 30-40 minutes, or until doubled in size. The dough should be visibly puffy and have risen to fill most of the mold.

Bake: Preheat your oven to 175 °C (350 °F). Bake the bread for about 15 minutes, or until the tops are golden brown and the bread sounds hollow when tapped. If the tops are browning too quickly, you can cover them loosely with aluminum foil during the last few minutes of baking.

Cool and Serve: Remove the bread from the oven and allow it to cool in the molds for a few minutes before transferring to a wire rack. Serve warm or at room temperature, enjoying the pillowy soft texture and the sweet, buttery flavor of the condensed milk bread.