Step 1

Use a food processor to pulse the biscuits to a crumb

Step 2

Melt the chocolate in a microwave-safe bowl in the microwave in 30-second bursts, stirring in between, or in a heatproof or stainless-steel bowl set over a pan filled with 1 cm (½ in) simmering water, stirring until melted. Mix in the oil and sea salt, followed by the digestive crumbs

Step 3

Pour the chocolate crumbs into a 23 cm (9 in) steel tart or pie case with removable base and press the mixture into the case with the back of a tablespoon. Leave to chill in the refrigerator to set

Step 4

Add the sugar and water to a high-sided saucepan, making sure there is no sugar on the sides of pan, and bring to the boil over medium-high heat

Step 5

Warm the soy milk (in another pan over a low heat until it is 60°C (140°F) on a thermometer

Step 6

Continue cooking the sugar syrup until it thickens and starts to colour (the time varies but it shouldn’t take more than a few minutes), then reduce the heat while it caramelises. It will become a deeper golden colour quite quickly. Remove from the heat and carefully start whisking the hot milk into the caramel gradually in a stream until it is all incorporated. Be very careful as it will boil and spit.

Step 7

Mix the remaining soy milk (and cornflour together in a small cup, then, while whisking, pour it into the caramel mixture. Return to the heat and cook, stirring constantly, until it thickens. Remove from the heat and add the vanilla, coconut oil and sea salt. Leave at room temperature in the pan to cool slightly, to 50°C (122°F). Whisk gently to start as the coconut oil will make the liquid slosh around. Gradually pick up speed and it will come together. Keep whisking until it is glossy and smooth and it sticks to the side of the pan.

Step 8

Using a silicone spatula, scrape the caramel custard into the chocolate digestive-lined base. Spread gently to level. The base and caramel filling can be prepared the day before, but it should be served the same day that it is finished with the bananas and cream.

Step 9

Slice the bananas and layer them all over the custard.

Step 10

Whip the cream in a stand mixer fitted with a whisk attachment to medium peaks, then dollop on top of the fresh banana.

Step 11

Use a vegetable peeler to shave chocolate over the cream, then leave to chill in the refrigerator for 30 minutes to set a little further. Place the tart case on top of a small dish to help push the base upwards to remove it from the tin and place the tart on a serving dish. Serve chilled on the same day it is made.