Preheat the oven to 350 degrees F. Grease two 9 x 13 inch cake pans with butter and line with parchment paper, allowing some to hang over each side for easy removal later.
Cream the butter, sugar, vanilla extract, and egg yolks together in the bowl of a stand mixer or in a large bowl with a hand mixer. Break up the almond paste with your fingers, and add to the mixture, mixing until the mixture is light and fluffy.
In a separate bowl, whisk together the almond flour and salt. Using a wooden spoon, stir the flour into wet mixture.
Using a hand mixer, beat the egg whites until stiff peaks form. Fold this into the batter until incorporated.
Split the batter in half, and spread it out between the two prepared baking pans. Bake for 20-30 minutes, until slightly golden and cooked through. Do not hesitate to cook the sponge a little longer if it feels undercooked. Remove the finished cake from the oven and allow to cool completely.
Once room temperature, lift the sponge cakes from the pans using the parchment paper and place them on a clean surface. Spread the jam over the surface of one of the cakes in a thin, even layer. Lift and place the second cake over the first, sandwiching the jam in the center. Press gently.
Using a double boiler or a heat-proof bowl set into a pot of water, melt the semi-sweet chocolate chips, stirring with a rubber spatula until smooth.
Using the same spatula, delicately spread the melted chocolate over the top of the sponge cake in a smooth, thin layer. To hide imperfections, you can trace ridges into the chocolate like I did in mine if you like.
Chill the entire layered “cake” in the fridge until the chocolate completely hardens (30 minutes to an hour).
Once the chocolate has set, place the whole cake onto a cutting board. Using a hot knife (as described below), first slice off the ugly edges, so that the sides will be cleanly visible. Snack on those remnants as you work. Then carefully slice the cookies into 2 x 2 inch squares.
Store the cookies in an airtight container with parchment or wax paper between layers. Cookies will keep 3 days at room temperature, and up to 7 days in the fridge.