I was going to wait until the 1st of December to post this, but I just couldn't wait to get started on my Christmas Postings. :)
When I was little, I had these layered squares at a family Christmas party, and was TOTALLY  blown away by them!  The next year, I asked my Aunt Elaine what they were called - and while I had the name for almost 2 decades, I didn't get the recipe until recently!  
I finally tracked them down in 
Company's Coming: 150 Delicious Squares by Jean Pare (her 
Company's Coming books are a super-popular series of cookbooks here in Canada, I think 
everyone has at least one book in the series in their cupboards!  I have several - there's tons of simple recipes that taste great without a lot of fuss). :)  Check them out here: 
Company's Coming.  These are sure to be a hit at your next holiday party!
Tweed Squares (recipe makes 36 squares)Base:1/2 cup butter
2/3 cup granulated sugar
1 1/3 cups all-purpose flour
2 tsp baking powder
1/2 tsp salt
1/2 cup milk
2 egg whites
2 squares of semisweet chocolate, grated
• Cream butter and sugar until blended.
• Combine flour, baking powder and salt. Add flour mixture and milk alternately to creamed mixture.
• Beat egg whites until stiff. Fold into batter. Fold in grated chocolate. Pour into greased 9x9" pan. Bake in 350 deg F oven for about 35 minutes. Cool.
Icing:1 1/2 cup icing (Confectioner's) sugar
3 tbsp butter 
1/2 tsp vanilla 
5 tsp water 
2 semisweet chocolate squares
1 tbsp butter or margarine
paraffin wax, size of a marble (optional, it's to make the chocolate shiny)
• Beat first 4 ingredients together in bowl, adjusting water as neeeded.  Spread frosting over cooled squares. 
• Melt next chocolate squares, butter/margarine, and wax (if using), in saucepan over low heat. Spread over the white icing.  Allow to set before cutting.