Chocolate Hazelnut Calzone with Bananas

Dough

• 1 oz olive oil, plus extra to grease
• 16 oz bread flour
• 2 ½ oz whole wheat flour
• 9 oz warm water
• ½ oz sugar
• 2 ¼ tsp rapid rise yeast
  or 1 packet/envelope rapid rise yeast
• 2 tsp salt

Calzone

• 12 tbsp hazelnut and chocolate spread (Nutella®), (approx. 12 oz ), divided
• 2 bananas, cut into ¼ in. rounds, divided
• 1 large egg, lightly beaten
• 1 oz turbinado sugar (optional)