Preheat the oven and prepare the baking dish. Set your oven to 180°C (160°C fan/gas mark 4). Lightly butter a 2-litre baking dish (roughly 28 x 18 cm). The butter helps prevent sticking and adds a subtle richness to the edges.

Prep the pears. Peel the pears, then cut them into quarters and remove the cores. Slice each quarter into 1.5 cm chunks. You want pieces thick enough to survive the baking time but small enough to meld with the cranberries. As you cut, you should hear the knife crunch through the crisp flesh.

Make the fruit filling. In a large mixing bowl, combine the pear chunks, cranberries, caster sugar, cornflour, lemon juice, vanilla paste, cinnamon, and salt. Stir gently with a wooden spoon until the sugar clings to every fruit piece. The cornflour will create a pale, dusty coating at first—this disappears as the fruit releases its juice during baking, thickening the syrup.

Build the crisp topping. In a separate bowl, whisk together the plain flour, rolled oats, brown sugar, and ground ginger. Drop in the cold butter cubes. Using your fingertips, rub the butter into the dry mixture until it resembles coarse, damp breadcrumbs. Some larger pea-sized butter lumps are fine—they create crunchy clusters as the topping bakes. You should see specks of butter still visible throughout.

Layer the crisp. Tip the fruit mixture into the prepared baking dish and spread it into an even layer. Spoon the oat topping evenly over the fruit, taking care not to press it down. A loose, craggy surface bakes into a more textured, golden crust.

Bake until bubbling and golden. Place the dish on a baking tray to catch any drips. Bake for 40–45 minutes. At the 20-minute mark, the topping will have turned a pale honey colour and the cranberries will start to pop. By 35 minutes, you'll hear the filling bubbling audibly and see ruby-coloured syrup seeping around the edges. The topping should be deep golden brown and feel firm to a light touch.

Rest before serving. Remove the crisp from the oven and let it stand for at least 15 minutes. This resting period allows the juices to thicken and settle; a crisp served piping hot from the oven will be too runny. The surface will appear slightly sunken in patches where bubbles have burst, which is exactly what you want.