Make caramel: In a small saucepan over medium heat, combine ½ cup sugar and water. Cook without stirring until the syrup turns golden amber. Immediately pour into the bottom of a 6‑ to 7‑inch flan pan and swirl to coat evenly.

Prepare squash: Steam or microwave the kabocha until tender, then puree with milk and cream until smooth.

In a medium bowl, whisk together eggs, remaining ½ cup sugar, vanilla extract, and salt. Stir in the squash puree until combined.

Pour the mixture over the set caramel in the pan.

Wrap the pan securely in aluminum foil to prevent water from entering during cooking.

Place 1 cup of water in the Instant Pot and set the trivet inside. Gently lower the flan pan onto the trivet.

Seal the lid and cook on high pressure for 25 minutes. Let it naturally release pressure for 10 minutes, then carefully quick‑release any remaining pressure.

Remove the pan and allow it to cool to room temperature. Then refrigerate for at least 2 hours (or overnight) to fully set.

To serve, run a thin knife around the edges and invert onto a serving plate, revealing the luscious custard topped with glossy caramel. Slice and enjoy!