Place the frozen bread dough loaves on a tray and allow them to thaw at room temperature for 3–4 hours, or thaw overnight in the refrigerator.

Lightly grease 9-inch loaf pans with non-stick cooking spray and set aside.

Using a sharp knife, cut four deep slits into each loaf, cutting nearly through while keeping the bottom intact.

Thoroughly coat each loaf with the melted butter, ensuring the butter reaches inside all cuts.

In a wide dish, combine the granulated sugar and ground cinnamon. Gently roll each butter-coated loaf in the cinnamon sugar mixture, applying a thick, even coating. Pack additional cinnamon sugar into each slit.

Place one loaf into each prepared pan. Cover loosely with a light kitchen towel and allow the dough to rise in a warm area until doubled in size, approximately 1 hour.

Preheat the oven to 350°F (175°C).

Bake the bread for 20–25 minutes, or until golden brown. When tapped on the bottom, the loaf should sound hollow. Remove from the oven and allow to cool in the pan for 10 minutes.

While the bread cools, prepare the icing by whisking together the powdered sugar, vanilla extract, and 2 tablespoons of milk. Add additional milk gradually until the desired drizzle consistency is achieved.

Drizzle the icing over the warm bread and serve immediately.