Makes: 30 servings. Prep Time: 2 hours. Bake: at 350° for 35 minutes. Chill: several hours.
Heat cream in small saucepan over medium-low heat until tiny bubbles begin to form around edge of pan.
Meanwhile, place chopped chocolate in food processor. Whirl until finely chopped. With machine running, slowly pour in hot cream through feed tube, blending until smooth. Divide mixture between 2 small bowls, about 1-1/2 cups each. Cover with plastic wrap; refrigerate until very cold, about 2 hours.
Heat oven to 350°F. Lightly coat 13 x 2-inch star cake baking pan (see Buyers Guide, page 145) and 9 x 9 x 2-inch square baking pan with cooking spray. Line bottom of pans with waxed paper. Lightly coat with cooking spray; lightly dust with flour.
Combine cake flour, sugar, baking powder, salt, 1-1/4 cups milk and the shortening in large bowl. Beat at low speed until blended; then beat on high speed for 2 minutes.
Combine lemon rind, remaining milk and egg whites in small bowl. Gradually add to batter and beat on high speed 2 minutes longer, scraping down sides of bowl occasionally. Pour 5-3/4 cups batter into star pan; pour remaining batter in 9-inch square pan.
Bake in 350°F oven 35 minutes or until toothpick inserted in centers tests clean. Cool cakes in pans on racks 15 minutes. Remove cake from pans to racks. Let cool completely.
Cut star-shaped piece of cardboard, using bottom of star pan as pattern. Wrap cardboard star in plastic wrap. Place large star cake layer, flatter side up, on top of covered cardboard star. Enlarge star pattern, this page, 200%. Using sharp knife, trace outline on cooled square cake. Cut out star from cake; save trimmings for snacks. Place small star on flat surface.
Beat half of ganache mixture on medium speed, just until thick enough to spread, 1 minute; be careful not to overbeat or mixture will separate. Carefully spread thick coating of ganache over sides, top of both stars; avoid getting crumbs into ganache. Refrigerate until ganache is firm, about 1 hour.
Tape toothpick to foil-lined cookie sheet. Set 1 point of star cookie cutter on top. Melt 1-1/2 oz. white chocolate and 1-1/2 tsp. solid vegetable shortening. Pour into star; spread. Chill.
Place star cakes on rack over baking sheet. Pour remaining ganache over top of cakes; ganache should be thick but pourable. If too thick, very gently fold in 1 to 1-1/2 tablespoons heavy cream; avoid creating bubbles. Smooth ganache with long metal spatula to coat top, sides of cake. Scrape any ganache on baking sheets over cakes; spread. Refrigerate at least 1 hour, until almost firm.