In a large bowl, stir together the flours, herbs, and salt in a bowl. Using your fingertips, rub the butter into the flour until you have a mixture that resembles sand.
125 g white flour, 125 g wholemeal spelt flour, 2 tsp dry mixed herbs, ½ tsp salt, 110 g diced butter
Adding one tablespoon of cold water at a time, work the dough into a bowl. Knead until you have a smooth dough (you might need to add flour or water). If you are using dairy-free spread or butter, you will require less water for the dough.
3 to 4 Tbsp ice cold water
Wrap the dough into cling film and place in the fridge for 30 minutes.
In the meantime, make the watercress pesto (see note 1 for instructions).
Preheat the oven to 200°C/ 400°F.
Cut out 2 large pieces of parchment paper and place the dough in the middle of one of them. Place the second piece of parchment paper on top of the dough and roll out the pastry to a round shape of about 28 to 30 cm (11 to 12 inch) diameter and 6mm (¼-inch) thickness. Peel off the top sheet of parchment paper and slide the pastry with the bottom parchment paper on an oven tray or pizza tray.
Scatter the grated cheese all over the pastry.
100 g grated extra-mature cheddar cheese
Slice the tomatoes.
7 medium-size tomatoes
Leaving a 5 cm (2-inch) edge, arrange the tomatoes on top of the pastry.
Fold the pastry edge inward to create a border.
Trim any excess parchment paper from around the tomato galette.
Drizzle 2 tablespoons of olive oil on top of the galette.
2 Tbsp extra-virgin olive oil
Bake in the oven for 35 to 40 minutes until the crust is golden brown and the tomatoes are cooked through.
In the meantime, make the pesto drizzle: Mix 2 to 3 tablespoons of pesto with 2 tablespoons of olive oil to make the pesto pourable
2 to 3 tablespoons watercress pesto, 2 Tbsp extra-virgin olive oil
When the galette is cooked, drizzle the pesto on top.
Season the top of the galette with salt and pepper.
Salt & pepper
Add a few basil leaves on top of the tomato galette and serve.
Fresh basil leaves