To a food processor, add 1½ cups all-purpose flour and ½ teaspoon salt and pulse twice to combine.Add 5 ounces butter (cubed and cold) and pulse until the butter has absorbed all the flour.
Add 2 tablespoons iced water and pulse a few more times till fully absorbed.
Transfer the dough onto a worktop and compact it into a disc. Put it in an airtight container and let it cool in the fridge for 15 minutes.
MAKE FILLING
In a bowl, combine 1 cup ricotta, ½ cup grated parmesan, 15 leaves basil (finely chopped), the grated zest of 1 lemon, ½ teaspoon salt, and 1 twist black pepper. Set aside.
In another bowl, toss1 pound cherry tomatoes (halved) with 1 tablespoon extra virgin olive oil, ½ clove garlic (grated), ½ teaspoon dried oregano, ½ teaspoon salt, and ¼ teaspoon black pepper. Set aside.
MAKE TOMATO GALETTE
Preheat the oven to 400°F or 200°C.Put the dough between two sheets of parchment paper and roll it out with a rolling pin to about 13 inches or 33 cm wide.Transfer the dough and the sheet of parchment paper onto a baking sheet. Remove parchment paper on top.
Spread the ricotta mixture on the dough, leaving about 1.5 inches (3.5 cm) of space from the edges of the dough.
Arrange the tomatoes cut side up on the ricotta, drizzle with some tomato juice leftover in the bowl, and sprinkle with dried oregano.
Fold the edges of the dough over the filling. Help yourself by pulling in the corners of the parchment paper. Brush the pastry with milk or non-dairy milk.
Bake at 400°F or 200°C for 50 to 55 minutes, or until the crust is golden brown on top.Let cool down, then transfer onto a serving platter, garnish with fresh basil leaves and optionally some flaky sea salt before slicing and serving it.