Strawberry Chocolate Galette

Name: Strawberry Chocolate Galette
Ingredients: 1/2 cup unbleached all-purpose flour; 1/2 cup whole wheat pastry flour; 2 tablespoons sugar; 1/4 teaspoon kosher salt; 1 stick very cold unsalted butter, diced; 3-5 tablespoons ice water; raw sugar for sprinkling; 1 egg; 1 teaspoon water; 3 ounces dark chocolate; 1/4 cup heavy cream; 1 quart strawberries, hulled and sliced; squeeze of fresh lemon juice; 3 tablespoons sugar, more or less depending on sweetness of strawberries; 1 1/2 tablespoons cornstarch