For the base, if you are using a no-bake base, please increase the quantity of butter to 125 gm, so that all the biscuit will hold its shape properly and solidify when cold.
If replacing agar agar instead of gelatin, soak 10 gm of agar agar in 100 ml water. Melt on low flame till done. Whisk the cornflour into 150 ml milk and then add all to the mango mixture and cook till all looks smooth.
Skip the mango essence for the whipping cream if unavailable. Instead you can use 2 tbsp mango puree or any flavoring of choice.