Preheat oven at 180 °C.
In a mixing bowl, mix butter, margarine, sugar, vanilla and salt until light and creamy
Add 1 egg and mix
Add the flour and mix until a dough starts to form
Grease a 28cm springform with butter and line with parchment paper
Spread 2/3 of the dough in the form, lining the bottom and sides of the form
Refrigerate the rest of the dough
Peel and core the apples and slice them
Put half of the apples in the form, sprinkle the cinnamon on top and cover with the rest of the apples
Roll out the remaining dough until it is about 0.5 cm thick. Cut into 8 strips of 1.5 cm wide and make one long strip for around the top
Make a checkered pattern on top, putting the long strip all around the top
Brush with the remaining egg
Bake the cake for 60-75 min in the middle of the oven
Once out of the oven, let cool for about 1 hour