Preheat oven to 225 degrees, and set the oven rack to the middle position.
Mix cereals, nuts and sunflower seeds in a large mixing bowl.
In a measuring cup, mix together remaining ingredients until combined.
Pour the wet ingredients over the cereal, nut mixture and mix well with a spatula, to combine.
Spread the nut-Chex mixture onto a sheet pan and bake for 45-50 minutes, stirring at least twice to prevent the bottom from burning.
Let cool to room temperature and serve
Store any leftovers in an airtight container for up to two weeks.