For almond tarts, replace the dried-fruit mixture with 2/3 cup sliced blanched almonds and skip step 1.
Combine dried fruit, orange juice, cognac, and 1/4 teaspoon salt in a saucepan. Bring to a boil, stirring; reduce heat and simmer 2 minutes. Let cool, 15 minutes.
Cut marzipan into chunks. In a food processor, puree marzipan, egg, and remaining 1/2 teaspoon salt.
Butter two 10-inch tart pans with removable bottoms. Divide dough in half. Roll out one half (keep other half refrigerated) on a lightly floured surface to an 11-inch circle. Fit into bottom and up sides of a prepared pan. Fill with half of marzipan, then half of fruit mixture (or almonds for almond tart). Repeat with remaining dough and filling. Drape with buttered plastic wrap. Let rise in a warm spot until almost doubled, about 45 minutes.
Preheat oven to 375 degrees with racks in upper and lower thirds. Bake tarts, rotating pans once, until golden brown, about 20 minutes (15 minutes for almond tart). Let cool slightly on a wire rack before serving.