Whisk softened butter, brown and white sugar and salt until creamy.
Mix in eggs, one by one.
Mix in pumpkin puree.
Mix corn flour, spelt flour and baking powder and fold in pumpkin mixture.
Spread on baking tray with baking paper. (I used also a baking frame.)
Bake in preheated oven at 180° C for about 35 minutes.
Leave to cool.
Roast pumpkin seeds in a coated pan without fat.
Add sugar and caramelize.
(If the sugar crystallize, add 1 tbsp water and stirr until it evaporates and caramel is clear.)
Put on baking paper to cool. Careful, very hot!!
Whisk softened butter and powdered sugar until creamy.
Fold in the cold cream cheese. (Don't stir too long, it might become fluid.)
Spread frosting on cake. Cut cake in bars.
Chop brittle and decorate bars.