Rinse glutinous rice 3–4 times and soak overnight.
Steam rice for 20–25 minutes until translucent and chewy.
In a pan, heat 1 cup coconut milk with sugar and salt; bring to simmer.
Add ube spread and extract (optional); stir until combined.
Add steamed rice into the mixture and stir until thickened.
In a separate pan, heat ½ cup coconut milk with sugar for sauce.
Add cornstarch slurry and stir until thickened.
Slice mangoes and portion into plates with rice.
Drizzle coconut sauce and top with toasted coconut if desired.
