Preheat the oven to 200C/180C Fan/Gas 6. Line an 8" Square Pan.
Start by melting the dark chocolate: break up the dark chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn’t burn. Set aside to cool whilst doing the rest:
Combine the melted butter, granulated sugar and light brown sugar in a large bowl/bowl of a stand mixer – on a medium speed for 3-5 minutes.
Add in the eggs and vanilla and mix again. Then add the melted chocolate, checking first that the chocolate isn't so hot as to cook the eggs. Mix again.
Fold in the flour, cocoa powder, a pinch of salt and the chopped milk and dark chocolate. Pour into the lined pan and bake 30 minutes. Remove and let cool on a wire rack.
Prepare the dips by warming in the microwave. Spreads (like Biscoff) will need about 20-40 seconds but check regularly as they are prone to burning. Melt the chocolate as before, in 20 second intervals, stirring in between!
Slice the brownies into 6x6 squares - or as big as you like! Serve immediately with the dips!