Melt butter in a small skillet over medium heat. Add pecans and cook for about four minutes until the pecans are toasted and the butter begins to brown.
Whisk in brown sugar, heavy cream, corn syrup, cornstarch and salt. Constantly whisking, cook until the sauce comes to a boil and thickens.
Turn off the heat and stir in vanilla extract. You can use it to drizzle on ice cream, pound cake, brownies — you name it!