Step 1: Preheat the oven
Preheat your oven to 200°C (180°C fan) or 400°F.
Step 2: Prepare the caramel
- Place the caster sugar in an ovenproof frying pan over medium heat.
- Allow it to melt without stirring, then add the butter, vanilla extract, and lemon juice.
- Stir gently until the caramel turns golden and smooth.
Step 3: Arrange the plums
- Place the plum halves cut-side down into the caramel.
- Sprinkle with cinnamon if using, then let them simmer for 5 minutes.
Step 4: Prepare the pastry
- Roll out the puff pastry (if not pre-rolled) and cut it into a circle slightly larger than the pan.
- Carefully place the pastry over the plums, tucking the edges inside the pan.
Step 5: Bake the tarte tatin
- Place the pan in the preheated oven and bake for 25-30 minutes, or until the pastry is golden and crisp.
Step 6: Flip the tarte tatin
- Let the tarte sit for 5 minutes, then carefully invert it onto a serving plate.
- Be cautious as the caramel may still be hot.
Step 7: Serve and enjoy
- Slice and serve warm with whipped cream or vanilla ice cream.