Mix all dry ingredients so they are evenly combined.
Crumble the butter into the dry ingredients using your fingertips only until pea-sized crumbs form.
Place mixture in a bowl and refrigerate for 10 minutes. Using the handle side of a wooden spoon, mix cold water into the flour mixture until it comes together. Using your hand, gently knead dough into a disc, and refrigerate about 10-15 minutes.
Slice Campari® tomatoes to ¼” (2/3 cm) thickness with a very sharp knife and set aside.
In a separate bowl, combine rosemary and thyme together.
On a clean surface lightly dusted with all-purpose flour, roll out dough to 10” (25 cm) circle. Thin the outer 1” (2.5 cm) of the circle so there is a thinner border.
Carefully transfer circle to a parchment lined baking tray. Refrigerate for 10 minutes.
Preheat oven to 375 °F/ 190 °C. In the centre of the dough, spread the breadcrumbs and leave a 1” (2.5 cm) border uncovered. Sprinkle half of the Parmesan on top of the breadcrumbs.
Starting from the centre, place the tomato slices in concentric circles, overlapping each slice by half, making sure the tomatoes cover the edge of the parmesan-breadcrumb mixture.
Sprinkle a pinch of ground black peppercorns and the mixed herbs over the tomatoes.
Sprinkle remaining Parmesan over the top of the tomatoes.
Lift the edges of the dough and fold them inward over the filling, pleating as you go, to create a folded-over border.
Brush edge of galette with beaten egg. Bake in preheated oven for 35 – 40 minutes, rotating pan halfway through. The edges of the dough should be browned and the dough cooked fully through.
Allow the Galette to rest for 10 minutes before transferring to a service board. Serve warm with Crème Fraiche.