Start with the salted caramel. Measure out the butter and cream and have on hand (separately) to add to the caramelised sugar when you need it

Place the sugar in a medium, heavy-bottomed saucepan and heat over medium-high heat. Leave the sugar completely undisturbed until it starts to melt. When you see it begin to caramelise, shake the pan from time to time so the sugar melts evenly – do not stir. Be very careful not to burn the sugar!

When the sugar is completely melted, continue to cook until the caramel is very fluid and dark golden brown – the darker the colour the more bitter the caramel will be, so you can adjust the cooking to your taste. If you start to see wisps of smoke, you are very close to cooking the caramel too much!

Remove from the heat and add the butter – stir to combine, making sure all of the butter is melted and incorporated

Add the cream and return to the heat, stirring constantly until the mixture is syrupy and homogenous. Set aside to cool. When the caramel has cooled enough to taste, add enough flaky sea salt to both balance the sweetness and add a touch of saltiness – you can adjust this to your taste

For the salted caramel pastry cream, put 1 tablespoon of the sugar in a medium bowl and set aside for later. In a medium, heavy-bottomed saucepan over medium heat, bring the milk, cream, the rest of the sugar and a tiny pinch of salt to a simmer, stirring once or twice to help the sugar melt and to stop the milk and cream burning on the bottom of the pan

While the dairy mixture is heating, add the yolks to the bowl with the reserved sugar and whisk until creamy. Add the cornflour and whisk until it is completely mixed in

Measure the butter and cut into medium pieces. Keep in the fridge until you need it. The butter must cold when you add it to the hot pastry cream. If it’s too soft, the fat will split as it melts too rapidly and there will be oily puddles in the cream

When the milk mixture has started to simmer, remove from the heat and whisk it into the yolks gradually to stop the eggs scrambling. Once incorporated, return to the pan

Return the pan to medium heat and cook the pastry cream, stirring the bottom with a spatula to help it cook evenly until the mixture has thickened and is just starting to bubble – that should take approximately 1 minute

Remove from the heat and whisk in the cold diced butter until completely incorporated

Add 60g of the reserved salted caramel and the vanilla extract and stir until the caramel has melted and mixed in completely with the pastry cream

Pass the pastry cream through a fine-mesh sieve to remove any stray chunks of sugar or lumps that may have been formed during cooking the eggs. The colour of the pastry cream will be clean, golden and speck-free

Pour the pastry cream into a bowl and cover the top with cling film, pressing it onto the top of the cream so a skin doesn’t form as it cools. Refrigerate for a minimum of three hours (or preferably overnight), to thoroughly chill and set the mixture

For the salted caramel glaze, warm 60g of the salted caramel slightly if it has cooled down and thickened since you made it. Stir in the icing sugar and mix until thoroughly combined with no lumps

To assemble the éclairs you will need 6 éclair shells (the link to the recipe to make these is mentioned in the introduction). To glaze the éclairs, carefully slice off the top third of each shell and press the top-facing side of each éclair into the glaze, making sure that side is completely covered

Carefully lay each glazed lid on a cake rack to allow the excess to drip off. The glaze will be shiny and a little tacky – it won’t dry completely, so be careful when moving

Scrape the pastry cream into a piping bag and twist the open plastic end to secure it. Cut a 1cm wide opening at the piping end

Pipe the pastry cream into each open éclair bottom, making sure that each tube is almost completely full

Carefully place the glazed tops back on each éclair and sprinkle with few flakes of sea salt and some fresh lemon thyme (a whole sprig if young and tender or a few picked leaves) to decorate

Serve immediately. They can be refrigerated to eat later, but are at their best when freshly made