Pastry time. Measure 200g of flour into a bowl or food processor. Cut 100g of cold butter into small cubes. Add to the flour then either blitz or rub together using your fingertips until breadcrumbs form. Mix in 1 tbsp of caster sugar and a pinch of salt then pour in 2 tbsp of cold water. Blitz or beat until it just comes together, if it looks a little dry add 1 more tablespoon of water. Tip the pastry out onto your work surface and briefly knead until smooth. Cover and chill in the fridge for 30 mins.

Meanwhile make your cookie dough. Toast the hazelnuts, if using, then leave to cool. Soften (don’t melt) the remaining 120g of butter in the microwave. In a large mixing bowl beat it with both the sugars until creamy. Crack in the egg, add the vanilla extract and mix to combine. Tip in the remaining 180g of flour, baking powder and a pinch of salt. Beat to form a cookie dough. Roughly chop up the chocolate and hazelnuts, then mix through the dough.

Preheat your oven to 180°C.

Get your pastry out of the fridge. Flour your surface. Roll out the pastry to roughly 1cm thickness and line a 20cm tart tin. Press the pastry into the edges of the tin. Cut off any excess pastry and patch up any holes, if you have any.

Spoon the Nutella all over the base of the pastry, then use the back of your spoon to roughly spread. Don’t worry about it being a super even layer as you don’t want to break the pastry.

Spoon the cookie dough over the Nutella layer. Bake in the oven for 35 mins until the top is golden brown, the edges are set and the middle still a little wobbly.

Serve warm with ice-cream or cooled with a cup of tea.