Start by making the base. Heat oven to 180 C/350 F and line the baking pan with baking paper.

Cut the semisweet chocolate for the base into chunks. Melt together with the oil using a double boiler method. Note that a microwave is not recommended as this can easily burn the chocolate. Once smooth and creamy, set aside.

Using a stand or hand mixer, cream together sugar and eggs. Once fluffy, add the salt and the potato flour. Finally, add in the melted chocolate and mix well.

Bake in the oven for 20 minutes for a brownie-like base. For a more cookie-like base, bake for an additional 3-4 minutes.

Remove from the oven and allow to cool.

Now make the filling. Place sugar and water into a small saucepan and bring to a boil over medium heat. 

While water is heating, begin mixing egg whites (stand mixer recommended) on low speed. 

Bring sugar mixture up to a temperature of 110 C/ 230 F. Use a candy thermometer or even a household infrared thermometer to check the temperature. You may need to increase the heat to achieve this. If you are unable to find a thermometer to use, you can also bring to a rapid boil for 4 minutes, but this is less accurate. Stir constantly to avoid burning the sugar.

The egg whites should now be white and fluffy. Reduce mixer speed to low. Pour in the sugar mixture in a slow, steady stream. Bring speed up to high and whip until stiff peaks , the mixture is shiny and it looks like marshmallow fluff (this could take up to 5 minutes). 

Assemble the filling and the base. Using the baking paper, lift the base out of the baking pan. Place on a flat surface. If you want bite-sized Crembo, use a cookie cutter (or glass) 3cm in diameter. For a larger size more similar to the boxed versions found in Israel, go for 6cm. Use the cookie cutter to cut out the bases of the Crembo. 

Prepare to pipe! Get your piping bag ready or simply cut a corner off of a Ziploc bag. Using a spatula, transfer the filling into the bag. For larger Crembo, pipe onto the base in a circular motion to create a cone shape approximately 7cm high (see picture for reference) or simply pick your desired ratio of filling to base. 

Place drying rack onto a baking sheet and place in a freezer for 60 minutes. 

Coat the Crembo with chocolate. While the Crembo are in the freezer, repeat the steps in making the base to melt the chocolate for the coating. Set aside.

Remove Crembo from the freezer. Pour the chocolate over each individual Crembo, allowing the baking sheet underneath the drying rack to absorb the excess. If not using a baking sheet, turn a small, shallow bowl upside down on top of a baking sheet. Place each Crembo on top and pour the chocolate over the top in the same manner. For more control you can spoon the chocolate on top. If you’re not so patient, you can pour in a slow stream from the saucepan itself (I personally find that this coats a bit more evenly). 

To dry quickly, place in the freezer for 5 minutes until set. Note that this will turn a shiny coating to look matte, but also adds a crispness to the coating.

If not serving immediately, and particularly if you live in a humid climate, place the Crembo into an airtight container and into the refrigerator. Crembo can be kept for a maximum of 2 days before serving.