Chocolate Babka (Chocolate Brioche Bread)

Name: Chocolate Babka (Chocolate Brioche Bread)
Prep time: 30 min
Cook time: 25 min
Total time: 55 min
Ingredients: 3 1/3 cup (530g) all purpose flour; 1/2 cup (100g) granulated sugar; 3 tsp (10g) instant yeast; 3/4 cup (175g) lukewarm water (90 degrees F); 3 large eggs; 10 Tbsp (150g) unsalted butter, room temp; 3/4 tsp (3g) fine sea salt; Neutral tasting oil for greasing; 6.5 oz (180g) dark chocolate (70 percent or higher); 1/2 cup (120g) unsalted butter; 3/4 cup (105g) powdered sugar; 1/2 cup plus 1 tbsp (42g) cocoa powder; optional freshly grated nutmeg (1/8 teaspoon); Pinch of salt