Preheat your oven to 350 degrees.
Line an 8x8 with parchment paper, spray the sides with some non-stick spray and set aside.
In a large bowl, cream together the butter and both kinds of sugar until combined, then add the egg, whisk together for about 30 seconds before adding in the flour, baking powder and salt and mixing to combine.
Using lightly floured hands, press the dough into your prepared pan and set aside.
Cream together the butter and sugar in the same bowl, then add the egg and both extracts, once all combined, add the ground almonds, flour and salt and whisk until combined.
Smooth the filling over the base, then sprinkle with sliced almonds and bake for 30 minutes or until golden brown and edges are set.
Allow to cool before slicing and serving.