Salted caramel apple galette

Name: Salted caramel apple galette
Ingredients: 1 pound apples (Empire or Pink Lady); Finely grated zest of 1 lemon; Juice of half a lemon; 1/4 cup brown sugar; 2 tablespoon Calvados (apple brandy); 1/2 teaspoon Saigon cinnamon; 1 tablespoon cornstarch; 2 tablespoon sanding sugar; 1 egg, lightly beaten; 1 tablespoon heavy cream; 1/2 cup granulated sugar; 2 tablespoon water; 1/2 cup heavy cream; 1/4 teaspoon salt; 3/4 cup spelt flour (if you don’t have spelt flour, you can replace with another wheat flour, nut flour like almond meal, or all purpose flour); 3/4 cup all purpose flour; 1 stick of butter; 2 tablespoon icing sugar; pinch of salt; 1/4 cup ice-cold water