Pour cereal into a very large mixing bowl and set aside.
Combine brown sugar, cinnamon, butter, and corn syrup in a saucepan.
Bring to a boil, stirring constantly.
Remove from heat and stir in soda and vanilla.
Pour over cereal and stir lightly till all pieces are coated.
Spread onto a greased cookie sheet with sides.
Bake at 250° for about 30 minutes, stirring every 10 minutes.
Pour onto waxed paper to cool.
Melt white chips in a glass bowl in the microwave at 50% power, stirring every 30 seconds.
Drizzle over cooled Chex mix.