Step 1

Preheat oven to 375 degrees F (190 degrees C). Butter 2 baking sheets.

Step 2

In a medium bowl, cream together butter and sugar until smooth. Beat in eggs one at a time, then stir in the milk, vanilla, and lemon extract. Combine cake flour and all-purpose flour, baking powder, and salt; gradually blend into the creamed mixture. Drop tablespoonfuls of the dough 2 inches apart on prepared baking sheets.

Step 3

Bake until edges begin to brown, about 20 to 30 minutes. Cool completely.

Step 4

Place confectioners sugar in large bowl. Mix in boiling water one tablespoon at a time until mixture is thick and spreadable. (Add more than the indicated amount if you need to).

Step 5

Transfer half of the frosting to the top of a double boiler set over simmering water. Stir in the chocolate. Warm mixture, stirring frequently, until the chocolate melts. Remove from heat.

Step 6

With a brush, coat half the cookie with chocolate frosting and the other half with the white frosting. Set on waxed paper until frosting hardens.