Whisk flour and salt together in a small bowl.
In the bowl of a stand mixer, cream softened butter and sugar.
Stir in egg, corn syrup and vanilla.
Add four to mixture 1/3 at a time.
Roll out dough between two pieces of waxed paper and refrigerate on a cookie sheet for 30 minutes.
Print out letter template onto thick card stock paper. Cut out shape.
Preheat oven to 375 degrees F.
Remove top layer of waxed paper from dough and sprinkle dough with flour.
Place template on top of dough and trace and cut out letter with a small, sharp knife. (Do not use a serrated knife.)
Turn letter onto cookie sheet and peel away waxed paper.
Re-roll dough and repeat with second letter. Refrigerate dough again if necessary.
Bake cookies for 8-10 minutes until done. Cool on wire rack.
Stir together 1 cup sugar and 1/4 cup water in a small saucepan. Boil over medium heat until it reaches 245 degrees F. (It is important to use a candy thermometer for this step.) As it cooks begin meringue so it's ready when syrup is done.
Whip egg whites with a wire whisk in a bowl of a stand mixer on high until soft peaks form. About 1-2 minutes. Sprinkle in 1/4 cup sugar. Beat.
Slowly pour the hot syrup into the meringue steadily with the mixer still on high.
Beat the frosting for 7-10 minutes until the outside of the bowl is room temperature.
Beat in butter by the tablespoon. The butter will deflate the frosting a bit, but soon you will have a perfect buttercream consistency for frosting or piping.
Add zest and juice of one lemon.
Fit a plastic piping bag with a size 1A piping tip. (I used Wilton brand for both.) Fill bag with buttercream and pipe round dollops of buttercream on bottom layer of your cookie until it is covered.
Carefully place second cookie on top of frosted bottom. Repeat with piping buttercream onto the cookie until it is covered.
Decorate your biscuit cake with flowers, fruits, cookies and almond slivers.
Cookie can be wrapped with plastic wrap and stored in the refrigerator for one week.