Mix the white sugar, brown sugar, half and half, and salt into saucepan.
Bring to a boil and reduce heat to medium continue to boil and still constantly until mixture thickens to a syrup, about 8 minutes. A candy thermometer should read 220° F.
Stir in butter, pecans, and vanilla. Continue to cook until mixture reaches 234° F.
Allow the glaze to cool for 5 minutes and pour over prepared bundt cake.