Preheat oven to 325 F
Prepare the shortbread: In a large mixing bowl, cream 1 cup butter & 3/4 cup sugar together until light and fluffy.
Blend in 2 cups flour and beat until thoroughly combined. Press the shortbread dough into a 13x9 baking dish.
Bake the shortbread dough for 25 min (or until golden brown). While the shortbread bakes, prepare the caramel topping.
In a medium pot, melt 3/4 cup butter over low heat. Once the butter is melted, add 1/2 cup sugar. Whisk to dissolve.
Once the sugar has disolved, turn heat to high, and pour in the 14 oz. of sweetened condensed milk and 3 tablespoons light corn syrup.
Bring the mixture to a full rolling boil that does not cease when stirred.
Once the mixture reaches that point, reduce the heat to a simmering level (medium-low heat).
Whisk the mixture at a simmer for 10-15 minutes - or until it reaches a caramel color. It is important to continuously whisk to prevent burning. You will know the mixture is ready once it begins to pull away from the sides of the pot. Do not remove from the heat early because your caramel will not "set" over the shortbread.
Once both the shortbread & caramel are ready, pour the hot caramel directly over the shortbread. Use a spatula to distribute evenly. Place into the freezer for about an hour.
Remove the caramel shortbread from the freezer and sprinkle salt over the top. Cut into small squares, and enjoy!