There is something magical about the bounty of fruit that is available over the summer, I obsess about cherries and get over excited about strawberries, my eyes are just so much greedier than my stomach. I would enjoy nothing more than simply lazing away the summer, baking and eating my way around the greengrocers, making a mixed berry sorbet for this week's dinner party, a cherry pie for the BBQ or maybe a peach and vanilla jam to see me through the colder months. The reality is, at least this year, a little different. The lot of a food writer is to develop recipes in advance, Valentine's Day dishes in December and Christmas recipes in the middle of July, so whilst you are in the park enjoying a picnic I’m in the kitchen pretending it’s snowing, Christmas songs playing in the background to keep me company. Because of this I crave everything seasonal. I bought a bunch of flat peaches with the idea of making some fresh summery dessert, but instead they sat on the kitchen counter, patiently waiting, but ended up as the topping for my breakfast granola. Rainier cherries were dealt the same fate, I just didn’t have time. Sometimes though an idea pops into my head that itches away so much that it begs to be made. This tart sprung to mind after seeing an Instagram picture from Tartine Bakery of blackberry and blueberry tarts, they were so beautiful, so pretty that I had to try them. 

In my new flat I've decided to have a little windowsill garden, well attempt one at least, my track record with living things is sketchy at best, I can kill even the hardiest of herbs. So far the garden is on the small side, home to just a few herbs, amongst them my current favourite, lemon verbena. The flavour is almost like a lemon sherbet, not sharp like the citrus itself, but herbal and punchy in flavour, delicious infused into ice cream, or made into a syrup for cocktails (some might describe it as artificial or soapy but if used correctly and not compared with lemon itself I think it is absolutely beautiful). For this recipe I decided to infuse the flavour into a lightened pastry cream, a nice pairing for the sweet and sharp fruits that decorate the tart.

(Note: Turns out Tartine makes the same suggestion for using lemon verbena in the custard, they have a recipe in their first book for a blackberry and rose geranium tart and in the introduction they make a suggestion for a blueberry and lemon verbena tart, very similar to the ones I saw in the picture and effectively for what appears here.)

Blueberry and Blackberry Tarts with Lemon Verbena

Makes 8

Sweet Pastry 
200g plain flour
20g ground almonds
40g icing sugar
1/2 vanilla bean or 1 tsp vanilla bean paste
125g unsalted butter, diced and chilled
1 large egg yolk
approx. 2 tsp ice cold water

Filling
500ml whole milk
10 lemon verbena leaves
200g caster sugar
2 large eggs
4 egg yolks
50g cornflour
300g blueberries
150g blackberries
Borage flowers (optional)
200ml double cream

To make the sweet pastry place the flour, almonds and icing sugar into the bowl of a food processor and pulse to combine. Scrape the beans from the vanilla pod and add to the food processor along with the butter (if using vanilla paste add this instead). Process until the mixture resembles coarse breadcrumbs then add the egg yolk and two tsp of ice cold water, pulse briefly until the mixture just starts to come together as a dough. Tip the mixture out onto the work surface and use your hands to bring together into a uniform dough, avoid overworking the dough and this will make the pastry tough and lead to it shrinking when it bakes. Form the dough into thick short sausage and wrap in clingfilm, refrigerating for a few hours before baking. 

To make the pastry cream place the milk, verbena leaves and half of the sugar into a saucepan and bring to the boil, remove from the heat and allow to infuse for about 20 minutes. Place the pan back on the heat and bring back to the boil. Meanwhile place the eggs, yolks, cornflour and the remaining sugar into a large bowl and whisk together until smooth. When the milk is at a boil pour through a fine sieve onto the egg mixture and whisk together to combine. Pour the custard mixture back into the saucepan and cook over medium high heat, whisking constantly until the mixture is very thick. Immediately scrape the custard into a clean bowl and cover with a piece of clingfilm, pressing onto the surface of the custard to prevent a skin from forming, placing the bowl into the fridge until fully chilled. 

Remove the chilled pastry from the fridge and cut into 6 slices. Roll each slice on a slightly floured work surface until about 3mm thick. Use the discs of pastry to line six 8cm wide tart tins (I use Matfer tart rings for a more professional look), trimming off the excess. Use the trimmings to repeat, using the pastry to line two further tart tins. Place the tarts shells onto a parchment lined baking tray and refrigerate for at least an hour or until firm.

When ready to bake and assemble preheat the oven to 180C (160C fan) and line each tart shell with a crumpled sheet of parchment paper, filling with baking beans or rice. Bake the tarts in the preheated oven for about 15 minutes before removing the parchment and beans and baking for a further 5-8 or so minutes or until the pastry is golden brown. Allow to cool before filling. To finish remove the chilled pastry cream from the fridge and beat to loosen. Very lightly whisk the cream until it is thickened but not yet holding soft peaks and in three additions, fold into the pastry cream. To assemble fill each tart shell with the lightened pastry cream (also known as crème légère or crème diplomat ) and top with a mix of blackberries and blueberries, decorating with the borage flowers if using. 

These tarts are best served within a few hours of serving as the pastry will begin to soften, if you need them to last a little longer brush the inside of the tarts with beaten egg yolk as they come out of the oven and place back into the oven for a minute or so to dry, this helps create a seal that will keep the pastry crisp for longer.