Cream butter and shortening until well blended. Mix in sugar and salt. Blend in eggs and extracts.

Mix flour with soda and cream of tartar and fold into batter to make a soft, but firm, dough. Roll dough into balls about the size of golf balls. Dip tops into sugar and place about 2 inches apart on baking sheet. Press very slightly (for crisper cookies) or not at all for slightly soft-centered cookies with crisp edges. (For easier handling, chill dough 15 minutes. Dough freezes well.)

Bake until edges are golden brown 12 to 16 minutes. Cool 2 minutes before removing from sheet. Cool on wire rack. Store in refrigerator. Makes about 2 1/2 large cookies.