Step 1 In the bowl of an electric mixer with a paddle attachment, combine the orange zest, butter and sugar. Beat until smooth.
Step 2 Add the eggs one at a time, beating after each addition.
Step 3Sift together the salt, baking powder and flour. Slowly add the flour mixture to the butter mixture, beating just until combined. Divide the dough in half and wrap separately. Chill for a few hours or overnight.