Step 1 Heat the oven to 350 degrees. Generously brush a 10-inch bundt or tube pan with the melted butter and dust with the ground almonds.
Step 2 Beat the butter in the large bowl of an electric mixer, gradually adding 2/3 cup of the sugar until creamy. Add the vanilla and mace and continue beating. Gradually beat in 1 2/3 cups of the flour until creamy and thick. Set aside.
Step 3In another bowl, beat the egg whites with the salt and cream of tartar until foamy. Gradually add the remaining 1 cup of sugar and beat until stiff. Add 1/4 of the egg white mixture to the butter mixture, mixing thoroughly with a rubber spatula. Fold the butter mixture into the remaining egg whites and sprinkle with the remaining 1 cup of flour. Gently fold together until completely blended. Fold in the caraway seeds, being careful not to over-mix. Pour into the prepared bundt pan.
Step 4Bake the cake until a toothpick inserted in the center comes out clean, 50 to 60 minutes. Cool in the pan 15 minutes, then carefully turn the cake out onto a rack. Just before serving, dust with the powdered sugar.