In a skillet over medium heat, toast rice flour, stirring frequently, for about 15 to 20 minutes or until color changes to pale gold and aroma becomes nutty. Set aside 1 cup for coating the espasol.
In a wide pan over medium heat, combine coconut milk, sugar, vanilla extract, and salt. Bring to a boil until sugar and salt are dissolved.
Slowly add 3 1/2 cups of the toasted rice flour, whisking vigorously to prevent lumps. Lower heat and continue to cook, stirring and turning regularly, for about 30 to 40 minutes or until mixture is very sticky and becomes oily.
Dust the bottom of a rectangular baking dish with 1/2 cup of the reserved toasted flour. Transfer mixture into the pan.
With a lightly-greased knife or spatula, spread and flatten the mixture evenly. Sprinkle with the remaining reserved toasted flour.
Cut the espasol into desired lengths and then roll on toasted flour to fully coat. Shake to rid of excess flour and wrap each piece in Japanese paper or banana leaves.