For the Dough:

1. Activate the Yeast:
   • In a small bowl, combine the warm milk and sugar. Sprinkle the yeast over the top and stir. Let it sit for about 5 minutes until the mixture is frothy and bubbly.
2. Mix the Dough:
   • In a large bowl, combine the melted butter, eggs, and salt. Add the yeast mixture and vanilla extract. Gradually add the flour, 1 cup at a time, stirring until the dough comes together. Once it starts to form, knead it on a lightly floured surface for about 5-7 minutes, or until smooth and elastic.
3. Let the Dough Rise:
   • Place the dough in a lightly greased bowl, cover with a kitchen towel, and let it rise in a warm place for about 1-1.5 hours, or until doubled in size.

For the Cinnamon Filling:

4. Make the Filling:
   • In a small bowl, mix together the softened butter, brown sugar, cinnamon, and salt until smooth and well combined.

To Assemble:

5. Roll Out the Dough:
   • Once the dough has risen, punch it down and roll it out on a lightly floured surface into a rectangle (about 12×18 inches).
6. Spread the Filling:
   • Spread the cinnamon filling evenly over the entire surface of the dough, leaving a small border around the edges.
7. Shape into Hearts:
   • Starting from one long side of the rectangle, carefully roll the dough into a tight log. Once rolled, use a sharp knife to slice the dough into 12 equal pieces.
   • To shape the rolls into hearts: take each slice of dough and carefully pull the sides of the roll out slightly, then fold the top of the roll down to form the top of the heart. The rest of the roll should form the bottom point of the heart. Place the shaped rolls into a greased baking dish, such as an 8×8-inch pan, to hold their shape.
8. Second Rise:
   • Cover the rolls with a towel and let them rise for about 30 minutes, or until puffy and slightly touching.
9. Bake the Rolls:
   • Preheat the oven to 375°F (190°C). Bake the rolls for 20-25 minutes, or until golden brown and cooked through.

For the Glaze:

10. Make the Glaze:
    • While the rolls are baking, whisk together the powdered sugar, milk, vanilla extract, and a pinch of salt in a small bowl. Add more milk if you want a thinner glaze.
11. Glaze the Rolls:
    • Once the cinnamon rolls are out of the oven and slightly cooled, drizzle the glaze over the warm rolls. If desired, you can garnish with sprinkles, crushed nuts, or a dusting of cinnamon.