Knead flour with rest of pizza base ingredients for 10 minutes until smooth and elastic. Cover and leave in a warm place for 40 minutes.
Roll out pizza dough into 2 bases. Cover and leave for 15 minutes.
Preheat oven to 190 C. Use your fingers to make indentations all over the dough. Brush base with melted butter and bake until crust is crisp and golden brown (around 20 minutes). Immediately top base with chocolate spread. Sprinkle with chocolate chips and put pizza back in oven for 1 minute until chocolate starts to melt.
Remove from oven, sprinkle with toasted hazelnuts, cut into generous wedges and serve.