Halve the passion fruits and scoop out the pulp into a fine sieve to extract 100-120 ml of juice.

Blend the mango pieces until smooth and set aside.

In a saucepan, combine the passion fruit juice, mango puree, white sugar, and mizuame. Heat gently until dissolved.

Prepare a slurry with cornstarch and water. Gradually pour this into the simmering mixture while stirring.

Reduce heat and add butter, stirring until melted and fully incorporated.

Pour the mixture into a lined tray and cool at room temperature for 1-2 hours.

Once set, cut into squares and roll in sugar if desired.