Preheat the oven to 350 F (180 C).
Butter and line with parchment paper 2 cake molds of 4 and 1/2 po x 8 po x 2 and 3/4 po (11 cm x 20 cm x7 cm).
Place the zest and sugar in a large bowl, mix well with your fingers so that the sugar is well impregnated with lemon, it’s humid, grainy and well flavored.
Add the eggs and beat with an electric mixer until the mixture is foamy and pale in color. Add the 35% cream, rum, and salt.
Whip until everything is well incorporated.

Sift together the flour and baking powder.
Incorporate this mixture into the previous preparation in 3 or 4 times.
You then get a thick and smooth mixture.
Finally, incorporate the melted and cooled butter in 2 or 3 times. Divide the dough into the 2 molds. Bake for about 50-65 minutes.
Check the cooking after 40 minutes.
If the cake browns too quickly, put aluminum paper on it.
Let the cakes cool on a grill after unmolding.
When the cakes are cooled, mix the powdered sugar with the lemon juice until a homogeneous and smooth consistency, and glaze the cakes.