Combine the cream and milk in a saucepan and place over medium high heat. Add the chopped hazelnuts and bring the cream mixture up to a gentle simmer. Remove from the heat, cover, and let steep for at least 1 hour or up to overnight. For best flavour, try to steep the hazelnuts for several hours.
After steeping, transfer the hazelnut cream mixture to a blender and blend until the nuts are finely ground. Pass the mixture through a fine mesh strainer, pressing down on the nut pulp to extract as much of the hazelnut cream as possible. Measure the hazelnut cream, adding equal parts milk and cream to make 2 cups total liquid.
Return the hazelnut cream to a saucepan and place over medium heat. Meanwhile, in a small bowl combine the egg yolks, sugar, and cornstarch. Whisk together well until the mixture looks pale yellow in colour.
Just before the hazelnut cream begins to boil remove it from the heat. Gradually temper the hot hazelnut cream into the egg yolk mixture. Add a small splash of the hazelnut cream and whisk it in completely before repeating. Do this until most of the cream has been added.
Return the mixture to the saucepan and continue to cook over medium heat, stirring constantly. Bring the custard up to a boil and then turn the heat off. Add the butter and Frangelico and whisk together. Pour the custard into a bowl and cover with a layer of cling film to prevent a skin from forming.
Hedgerow Crumble
Preheat the oven to 350°F. Spray an 11″ by 7″ baking dish with non-stick spray and set aside. In a mixing bowl, combine 1 1/2 cups of the flour with the brown sugar, chopped hazelnuts, 1 tsp cinnamon, allspice, and kosher salt. Add the melted butter and mix together to make a crumble. Set aside.
In a mixing bowl combine the apples, blackberries, and raspberries. Drizzle with the lemon juice and sloe gin. Add the granulated sugar, the remaining 3 tbsp flour and 1 tsp cinnamon. Stir together until the dry ingredients coat the fruit.
Transfer the fruit mixture to the prepared baking dish. Top with the crumble and bake for 45 to 50 minutes until the fruit is bubbly around the edges and fully cooked.
The hazelnut custard can be served either cold or warmed up. Top each serving of hedgerow crumble with a generous dollop of the hazelnut custard and enjoy!
Notes
*Frangelico, or hazelnut liqueur, adds to the overall flavour of the custard, however it can be omitted to make the recipe non-alcoholic - there will still be hazelnut flavour without it.**If you don't have sloe gin you can substitute with either blackberry liqueur or blackcurrant liqueur (such as crème de cassis). To make it non-alcoholic, simply omit the liqueur.