Orange Chocolate Cupcakes

Preheat oven to 375°F with rack in middle. Line a 12-cup muffin tin with paper liners.

Beat butter with 10 tablespoons sugar and egg yolks with an electric mixer on medium speed until light and creamy, about 3 minutes. On low speed, mix in matzo cake meal, orange zest and juice. With clean beaters, beat egg whites with salt in another bowl just until soft peaks form, then gradually beat in remaining 2 tablespoons sugar just until stiff. Fold 1/4 of whites into butter mixture to lighten, then fold in remaining whites gently but thoroughly. Fold in chips.

Spoon into muffin cups and bake golden and until a wooden pick inserted in center of cupcakes comes out dry, about 25 minutes.

Remove cupcakes from tin and cool on a rack.

Cooks' notes: Cupcakes can be made 3 days ahead and kept, at room temperature, in an airtight container.

If you can't find matzo cake meal, simply whirl broken matzos in a blender until powdered.