• Preheat the oven to 350 °F. Line a half sheet pan with parchment paper or butter and flour the pan.
• Cream 6 oz almond paste until softened and smooth. With the mixer running, add 6 oz unsalted butter and mix on low until there are no lumps of almond paste. Add 6 oz confectioner's sugar and increase the speed to medium. Cream until light and aerated. Scrape down the bowl and paddle.
• Add 6 eggs in three batches, scraping the bowl and mixer between each addition. Add ½ teaspoon table salt, 1 teaspoon vanilla extract and 1 teaspoon lemon extract and mix to combine. Add 4 ½ oz cake flour all at once and mix just until incorporated.
• Spread the batter onto the prepared sheet pan. Try to get the batter as even and flat as possible. The flatter the cake bakes the better the finished petit fours will look.
• Bake until the cake is lightly browned and springs back when the center is pressed, about 15 minutes. Cool the cake completely in the pan.

Assembly

• Place a piece of parchment paper on top of the cake in the pan. Flip the cooled cake from the pan onto a work surface. Peel off the used parchment paper and leave the cake, with the clean parchment underneath, bottom side up on the work surface.
• With the long side of the cake facing you, slice the cake down the middle. Spread 1 cup strained apricot preserves onto one piece of the cake. Place the other piece of cake on top. Spread 1 cup strained apricot preserves onto the top of the cake. Set the cake in the freezer for 30 minutes to firm it up.
• Remove the cake from the freezer. Trim the uneven edges of the cake. Use a ruler to mark of 1½" increments across the top edge of the cake. Use a long serrated knife to cut the cake into 1½" inch strips. Turn the cake so the strips are now horizontal to you. Use a ruler to mark of 1½" increments. Use a serrated knife to cut the cake into 1½" inch squares.
• Lift each square and place on a cooling rack set over a clean sheet pan or a large bowl. Leave at least ½" between each cake square. Use freshly made fondant or warm the fondant to 100 °F (slightly warmer than body temp). Put the fondant into a container with a pouring spout.
• Slowly drizzle the icing over each square. Work slowly pouring back and forth and over each corner. Continue covering squares until you run out of icing. As you work, if you see any gaps in the cakes use a small spatula to filling them in with more icing. You can reuse the icing from the bowl or the sheet pan under the cakes to finish icing all the petit fours.
• Allow the icing to set completely. You should be able to lightly touch the icing without it sticking to your finger. Use a small spatula to lift each petit four and set them into small paper cups or onto a serving tray. Decorate the petit fours as desired. Store at room temperature until ready to serve.