In a food processor, combine all-purpose flour, parmesan cheese, Italian seasoning, black pepper, sugar, and kosher salt; pulse until well mixed. Next, add very cold, diced unsalted butter and pulse until the mixture resembles coarse crumbs. Gradually add chilled ice water, pulsing until the dough just forms a ball.

Shape the dough into a disk about an inch thick, then wrap it tightly in plastic wrap. Refrigerate for at least 1 hour to let the gluten relax.

In a skillet over medium heat, add olive oil and sauté thinly sliced onion until it becomes golden and soft, about 5–7 minutes. Stir in minced garlic and cook for an additional minute until fragrant.

Preheat your oven to 400°F (200°C). On a lightly floured surface, roll out the chilled dough into a roughly 12-inch circle. Spread the onion and garlic mixture evenly across the dough, leaving a 2-inch border. Sprinkle white cheddar cheese, layer with sliced tomatoes, and season with fresh thyme, parsley, chives, salt, and pepper to taste.

Fold the edges of the dough over the filling, creating a rustic crust that cradles the tomato goodness. Brush the crust lightly with heavy cream for a golden finish.

Place the assembled Tomato Galette on a parchment-lined baking sheet and bake for 40–45 minutes until the crust is beautifully golden and the filling is bubbly.

Once baked, remove your Tomato Galette from the oven and let it cool for about 10 minutes on a wire rack.

Serve warm or at room temperature, enjoying the delightful combination of flaky crust and juicy, flavorful filling.