In a large mixing bowl, whisk together 4 large eggs, 1 cup of whole milk, 1/4 cup of granulated sugar, 1 teaspoon of pure vanilla extract, 1 teaspoon of ground cinnamon, and a pinch of salt until smooth and well combined.

Take your day-old classic glazed donuts and slice them in half horizontally. Dip each donut half into the custard mixture, allowing it to soak for about 20-30 seconds on each side.

Preheat a non-stick skillet or griddle over medium heat (around 350°F). Add a tablespoon of unsalted butter and allow it to melt.

Carefully place the soaked donut halves slice-side down into the hot skillet. Fry them for about 2-3 minutes until they turn golden brown.

In a medium saucepan over medium heat, add 1 cup of granulated sugar and allow it to melt, stirring gently until it becomes a deep amber color. Remove from heat and carefully whisk in 6 tablespoons of unsalted butter and 1/2 cup of warmed heavy cream until smooth.

Once your crispy donut French toast is ready, arrange the golden halves on a serving plate. Drizzle the warm salted caramel sauce generously over the stacked donuts.