Panna cotta: Preheat the stove all products for the panna cotta to boiling. Remove from heat and add gelatin, previously dissolved in 2-3 tbsp water. Cool well and put in refrigerator to harden slightly cream. Cream Pastichera: Heat the milk with the lemon peel. Separately, beat egg yolks with sugar, add the flour and mix well. Carefully pour the milk into the egg mixture and return to the heat. Stir until it boils and thickens the cream. Cool slightly. Mix both the cream and mix well. Pour the cream into a form of your choice and place it in the refrigerator for several hours. Serve with caramel sauce. The dessert may be frozen.