Grease 5 cup heart shaped pan; dust with unsweetened cocoa powder and set aside.
In bowl, blend together brown sugar, butter and vanilla; add eggs, one at a time, beating well with wooden spoon after each addition.
Sift together flour, cocoa and salt; add all at once to creamed mixture, mixing just until blended. Stir in nuts; spread in prepared pan. Loosely cover tip of heart with foil to prevent from drying out.
Bake in 350°F oven for 35 to 40 minutes or until just barely firm to the touch. Let cool in pan for 10 minutes; turn out onto rack and let cool completely.
On top of double boiler over hot, not boiling, water, melt white chocolate with butter. (Alternatively, in microwaveable dish, microwave at Medium/50% for 1 to 2 minutes or until softened.) Remove from heat and let cool slightly; stir in sour cream until smooth and blended.
Refrigerate for 10 minutes; spread smoothly over sides then top of cooled cake. Sprinkle cocoa in attractive pattern on top of cake. Arrange almonds around top edge.