Preheat the oven to 375°F (190°C). Lightly butter a 9 × 6-inch baking dish.

Place the sliced apples and pears in the baking dish. Add the brown sugar, cornstarch, lemon juice, vanilla, cinnamon, cardamom, ginger, cloves and salt. Toss thoroughly until the fruit is evenly coated.

Cover the dish tightly with foil and bake for 15 minutes to begin softening the fruit.

Meanwhile, place the butter in a light-coloured saucepan over medium heat. Cook, stirring frequently, as it melts and foams.

Continue cooking until the milk solids at the bottom of the pan turn deeply golden and the butter smells nutty. Immediately pour it into a heatproof bowl, including all the browned bits. Let it cool for 10–15 minutes.

In a medium bowl, stir together the flour, oats, brown sugar, cinnamon and salt.

Pour in the warm brown butter and stir until the mixture is evenly moistened and forms large, irregular clusters.

Remove the fruit from the oven. Scatter the crumble evenly over the filling without pressing it down.

Return the dish to the oven and bake uncovered for 40–45 minutes. The crumble should be deeply golden, the filling should bubble through the centre and a knife should slide easily through the apples.

If the crumble darkens too quickly, loosely cover the dish with foil for the final 10 minutes.

Let the crisp rest for at least 30 minutes before serving so the fruit juices can thicken.

Serve warm with ice cream and a small pinch of flaky salt.