Preheat the oven to 150C/300F and spray an 8x8 inch square pan with cooking spray. You can also use softened butter to grease the pan. Sprinkle the pudding rice into an even layer over the base of the pan.
Place the sugar, milk and vanilla extract into a deep saucepan and place over a low heat. Warm gently until the sugar has dissolved. You don't want the mixture to even simmer, just be warm throughout. This took around 5 minutes on low heat. I dipped a clean finger in to check the temperature, you want to feel that it's pretty warm on your finger, but not scolding hot.
Gently pour the milk mixture over the rice. At this stage you have two ways of adding the cinnamon - you can sprinkle it on top now, then when you stir the rice pudding after 90 minutes and it will mix in with the rice. OR you can place straight in the oven for 90 minutes, stir it and then sprinkle the cinnamon on top if you want the skin to be cinnamon-y. Completely up to you, I sprinkled the cinnamon on top and baked it before stirring it in.
Bake for 90 minutes, then remove from the oven and gently stir. Place back in the oven for 30-45 minutes. Mine took 2 hours exactly, you want there to be no runny liquid and for the rice to be set, but still creamy looking. If you over cook it, it will look quite dried out!
Remove from the oven and put to one side while you make the spiced pear compote. Place the pears, lemon juice, cinnamon, sugar and water into a medium sized saucepan over a medium heat. Stir frequently and bring to a boil, reduce the heat to low and then simmer for 10-15 minutes until the pears are tender.
Leave the mixture to cool for 20 minutes. Baked Rice Pudding is best served warm, so after you've made the compote, it should be ready to serve. Divide the rice pudding between bowls and top with spiced pear compote.
The rice pudding will keep covered (without the spiced pear compote on top) in the fridge for 4 days, make sure to reheat thoroughly when you want to serve it. The spiced pear compote will keep in an airtight container, in the fridge for 4 days.