Place flour, salt, and butter in a bowl and, with a pastry blender or 2 knives, cut butter into flour until the largest pieces are the size of small peas. Add water and stir into flour butter mixture to combine. With your hands, form the dough into a ball, flatten and cover tightly with plastic wrap.
Refrigerate for 30 minutes.
Preheat oven to 375 degrees F. Place oven rack in center position.
Stir together ricotta cheese, Parmesan, basil, salt, and pepper.
Roll out the dough into a 15-inch round and place on a parchment lined baking sheet.
Spread the ricotta cheese mixture evenly over the dough, leaving a 3-inch edge for folding over.
Arrange the tomatoes, cut-side up, on top.
Fold the edge of the dough up onto the top of the tart. Brush with the beaten egg.
Place the galette in the oven and bake for 50 minutes until the crust is golden brown.
Serve hot.
Recipe by The Gardener Cook at https://www.thegardenercook.com/roasted-tomato-and-ricotta-galette/