To make the galette crust: mix together the dry ingredients (flour, salt). Using a pastry cutter or your fingers, cut in the cubes of butter until they are crumbly and pea sized. Mix in the ice cold water one tablespoon at a time, stirring with a wooden spoon until a cohesive ball of dough forms. Let rest in the fridge for 30 minutes.
Preheat the oven to 425°F.
Meanwhile, prep the filling: Slice the garlic cloves in half lengthwise. Heat the olive oil over medium heat in a large skilled. Add the garlic, cherry tomatoes, and balsamic vinegar. Saute just until the cherry tomatoes burst, about 8-10 minutes, stirring frequently. Mix in the fresh thyme.
On a lightly floured surface, roll out the pastry dough into a 12 inch circle. Place on a parchment paper lined sheet pan or on a preheated pizza stone.
Pour the cherry tomato filling into the center of the galette, leaving about 2 inches of a border. Fold the border in over the cherry tomatoes (see pictures for how it should look). S
Bake for 25-30 minutes, until the galette is golden brown. Remove the galette from the oven and allow to cool for 5-10 minutes before cutting.