Florentine Oat Biscuits: Preheat the oven to 375°F (190°C).
Line two baking sheets with parchment paper or silicone mats.
Melt the butter in a medium saucepan, then remove from heat.
Add the oats, sugar, flour, corn syrup, milk, vanilla extract, and salt to the melted butter.
Mix well.
Spoon the mixture onto the prepared baking sheets, spacing 3 inches (7.5cm) apart.
Gently flatten with the back of a spoon or a spatula.
Bake for 6-8 minutes, until the biscuits are golden brown.
Allow to cool completely on the baking sheets.
Once the biscuits are cool, top with hibiscus gel and passion curd to make sandwich biscuits.
Hibiscus Gel:
Reserve 1 tablespoon (15ml) of water from the initial amount and soak the gelatin in it.
Boil the water with the sugar and add the dried hibiscus flowers. Cover and let infuse for 20 minutes.
Strain, then add the gelatin that has been melted in the microwave for a few seconds.
Mix well.
Pour the hibiscus gel over the panna cotta, to a thickness of 1/4 inch (5mm), and refrigerate until set (about 2 hours).