Hazelnut Shortbread Sandwich Cookies (with chocolate ganache)

Ingredients:
For the hazelnut shortbread:
90 g toasted ground hazelnuts
135 g unsalted butter, softened
75 g light muscovado soft sugar
1 tsp vanilla extract
210 g AP flour
¼ tsp salt
For the chocolate ganache:
100ml. Heavy cream
150gr. Dark chocolate