Bilad al-Sham Kitchen - Mashed blueberries (blueberries)

Mashed blueberries (blueberries) 

A cup of flour 

A cup and a half of oats 

⅓  cup of sugar 

150 gm butter 

A pinch of cinnamon 

Filling: 

2 cups blueberries 

2 tablespoons  sugar 

2 teaspoons starch 

A tablespoon of lemon juice 

A teaspoon of lemon zest 

For face: 

½  cup fine sugar

1 tablespoon liquid milk