In a large mixing bowl, combine warm milk and granulated sugar, then sprinkle the active dry yeast over the surface. Let it activate for about 5 minutes until bubbly.

In another bowl, whisk together all-purpose flour and salt. Melt the butter and mix it with the activated yeast, followed by the egg. Pour this into the flour mixture, and knead until smooth, approximately 8-10 minutes, before letting rise in a warm place until doubled in size, about 1 hour.

Prepare the filling by mixing softened butter, granulated sugar, and ground cinnamon in a medium bowl until smooth and spreadable.

Once the dough has risen, punch it down gently, roll it out on a floured surface into a large rectangle, about ¼ inch thick, then spread the cinnamon filling evenly across it.

Starting from one long side, roll the dough tightly into a log. Cut the log into 2-inch pieces and shape each into a heart.

Place on a parchment-lined baking sheet and cover with a towel, allowing them to puff up for 30 minutes. Preheat your oven to 375°F (190°C) while they rise.

Bake the rolls for 15-20 minutes or until golden brown.

Prepare the icing by whisking together powdered sugar, vanilla extract, and a splash of milk until smooth. Drizzle over warm rolls.