Bolognese and egg calzone

Ingredients

• 1 cup lukewarm water
• 2 teaspoon dried yeast
• 1/4 teaspoon caster sugar
• 2 1/3 cup bread flour
• 1 teaspoon fine salt
• 1 tablespoon olive oil
• 10 gram butter
• 1 onion, sliced thinly
• 1 1/4 cup basic bolognese sauce (see recipe below)
• 4 eggs, plus 1 extra, beaten
• 1 cup grated mozzarella
• 1 cup cup kale, finely shredded