Put the semolina, sugar, baking powder, ground mastic (we grind it using a mortar and pestle, together with a spoonful of semolina because mastic is sticky) into a bowl and combine. 

Use another bowl to mix the milk and baking soda. 

Slowly pour the milk in and stir until it gets firm but spreads easily. 

Butter a baking tray of about 25Χ33 cm or a round of 32 cm and spread the mixture with a spatula so it is evenly distributed. A little trick to spread the mixture evenlytap  the bottom of the tray with your hand or on a hard surface 5-6 times so that it spreads by itself. 

Preheat the oven at 180-200°C (depending on the oven) using the convection feature and leave it to bake for about half an hour. 

Remove from the oven and let it cool. 

Put the syrup over the heat and boil for about 8 minutes. 

Pour the warm syrup over a cold cake little by little using a tablespoon and leave it to cool. 

Beat the ingredients for the custard for 5 minutes using a mixer. 

Pour the custard over the sweet and spread it with a spatula. 

Sprinkle with cinnamon and place in the fridge for a while so that the cream combines with the sweet.