Passover Chocolate-Walnut Cake with Orange

Name: Passover Chocolate-Walnut Cake with Orange
Prep time: 40 min
Total time: 40 min
Cuisine: Asian, Japanese
Ingredients: 0.75 cup safflower oil, plus more for pan; 1 cup matzo meal; 1 cup walnuts, toasted and finely ground; 0.75 cup sugar; 1 teaspoon ground cinnamon; 0.5 teaspoon coarse salt; Grated zest of 1 large orange, plus 1/4 cup fresh juice; 3 large eggs, separated, plus 3 large egg whites; 3 ounces semisweet chocolate, coarsely chopped (½ cup); 1 ounce semisweet chocolate, melted; 5 very thin orange rounds; 0.333 cup walnuts, toasted and coarsely chopped