First let’s make ice cream 24 hours before. Crush the cardamom pods, tip them into a saucepan and mix in the cream. Set over a low heat, bring to the boil, then remove from the heat. Cover and leave to infuse for 30 minutes.
Whisk the egg yolks with the sugar until they become pale and fluffy, then slowly stir in the cardamom cream. Return to a clean pan and place over a low heat. Keep stirring with a wooden spoon until the mix forms a thick custard.
As soon as it forms the thick custard, remove from the heat and tip into the bowl sitting on the ice. Keep stirring until it is tepid, then strain into a container.
Once cold, process the custard in an ice-cream maker, or in a pacojet beaker freeze it.
To make the sweet pastry- In a mixing bowl cream the butter and icing sugar and thyme together. Mix until very pale. While still mixing, slowly add the eggs a little at a time, making sure the first egg is fully combined before adding the second. Sift in the plain flour and mix well until you can form a smooth pastry ball. Flatten out the pastry with a rolling pin and Wrap in cling film and refrigerate for a minimum of 2 hours.
Once the pastry has rested, it is now ready to roll. First, butter a 10” flan ring which has a removable base. Lightly flour a worktop and a rolling pin. Unwrap the pastry and lay it on the surface. Roll the pastry out until you have a large circle 1/2 cm thick. Carefully place the pastry into the flan ring, making sure it goes all the way to the edges. Place the ring on to a tray and refrigerate for a further 30 minutes. Once chilled prick the bottom of the tart case with a fork about 10-15 times evenly across the base. Cover the tart case with baking paper and fill with baking beans. Again leave this to rest in the fridge until you have the treacle tart filling ready.
To make the filling gently heat the treacle, golden syrup and double cream in a heavy based saucepan for 5 minutes. Remove from the hob and while still warm, whisk in the eggs and then add the orange zest, lemon juice and breadcrumbs until all the mixture is incorporated.
Preheat the oven to 160ᵒC. To bake, take the baking bean-filled pastry case from the refrigerator and place into the middle of an oven then bake for 20 minutes. Take the case out of the oven, carefully remove the baking beans and return to the oven to bake for a further 10 minutes. Remove the case from the oven and carefully pour the treacle filling into the pastry case. Return the tart to the oven and bake for 30-40 minutes until the middle of the tart is just cooked. The top of the tart filling should look as though it has dried out and is beginning to crack.
Allow the tart to cool on a cooling rack then remove from the flan ring. Slice the tart into portions and serve with cardamom ice cream.