Grease the bottoms of two 9-inch round cake pans, then line with waxed paper. In a bowl, stir together graham cracker crumbs, baking powder and salt.
In a food processor or in a large bowl using an electric mixer, cream together butter and brown sugar until mixture is light and fluffy. Beat in egg yolks, one at a time, beating well after each addition. Stir in crumb mixture in batches, alternating with milk. Stir in vanilla.
In a separate bowl, beat egg whites with cream of tartar until mixture just holds stiff peaks. Stir 1/4 of mixture into batter, then fold in remaining whites gently but thoroughly. Divide batter between prepared pans and bake in the middle of a 350-degree oven for 20 minutes. Let cool before assembling cake.
For glaze: Cook brown sugar, cream and salt until mixture reaches the soft ball stage. Remove from heat and add butter and vanilla. Cool for about 15 minutes without stirring, then beat by hand until smooth.
In a separate bowl, beat cream and powdered sugar to make whipped cream.
After cake and glaze have cooled, place cake layer on a stand. With the back of a spoon, spread glaze so that it drizzles over edges of cake. Then add whipped cream layer. Add next cake layer and glaze it. Put remaining whipped cream in a pastry bag and make a free-form design on top.
SERVES: 8 - 10