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Put oven rack in middle position and preheat oven to 350°F.
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Spray a 13- by 9-inch baking pan with nonstick cooking spray and line bottom with parchment paper, leaving a 2-inch overhang on 2 ends, then spray the paper.
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Beat whites in mixer fitted with whisk attachment at medium-high speed until they just hold stiff peaks. Add ¼ cup sugar a little at a time, beating at high speed until whites hold stiff, slightly glossy peaks. Transfer to another bowl.
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Switch to paddle attachment, then beat together almond paste and remaining ¾ cup sugar until well blended, about 3 minutes.
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Add butter and beat until pale and fluffy, about 3 minutes.
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Add yolks and almond extract and beat until combined well, about 2 minutes.
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Reduce speed to low, then add flour and salt and mix until just combined.
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Fold half of egg white mixture into almond mixture to lighten, then fold in remaining whites gently but thoroughly.
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Divide batter among 3 bowls. Stir food coloring into each bowl.
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Pour 1st colored batter into prepared pan and spread evenly with offset spatula (layer will be about ¼ inch thick).
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Bake each layer 8 to 10 minutes, until just set. (It is important to undercook.)
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Transfer to a rack to cool.
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When all layers are cool, invert 1 layer onto a wax-paper-lined large baking sheet. Discard paper from layer and spread with half of preserves.
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Invert next on top of 1st layer, discarding paper. Spread with remaining preserves.
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Invert final layer on top of previous layer and discard wax paper.
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Cover with plastic wrap and weight with a large baking pan. Chill at least 8 hours.
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Remove weight and plastic wrap.
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Bring layers to room temperature.
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Melt chocolate and shortening in the microwave for 1 minute. Stir until smooth. If chocolate needs to be melted more, place in microwave and heat for increments of 10 seconds until it is smooth.
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Trim edges of assembled layers with a long serrated knife.
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Cut into 2 inch squares then carefully dip into chocolate to coat.
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Once all of the squares have been coated, melt about ⅓ cup of white chocolate coating with shortening and pink food gel.
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When melted and smooth, place in a ziplock bag and snip the corner.
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Drizzle pink chocolate onto the squares and top with you favorite sprinkles.