Get ramekins ready to go.
Pour sugar into a medium sauce pot and set to medium-low heat. Let the sugar dissolve, gently swirling the pot but not stirring, until mixture turns a deep golden color, 8 to 9 minutes.
Immediately remove pot from heat and pour caramel into ramekins. Gently lift and tilt ramekins to coat the inside with caramel. Set aside.
Combine coconut milk and agar agar in a medium sauce pot.
In the blender combine the oatmilk, sugar, chickpea flour, and vanilla. Process until smooth. Pour this mixture into the pot with the coconut milk.
Bring mixture to a simmer for 5 minutes, then remove from the heat. Let cool slightly, then pour into ramekins.
Place ramekins in the fridge for 4 hours to let the flan set.
To serve, place bottom of ramekin in a container with hot water for 1 -2 minutes, in order to release the flan.
Use a small knife or offset spatula to carefully loosen the edges of the flan. Turn flan over onto a plate, shake gently to release flan and remove ramekin.