Marbled chocolate brioche

Chocolate filling (water, semisweet chocolate chips [sugar, chocolate liquor, cocoa butter, natural flavoring, soy lecithin], sugar, egg whites, modified potato starch, sweetened cocoa powder (sugar, cocoa powder), milk, whey, natural and artificial flavorings, xanthan gum, maltodextrin, soy lecithin, beta-carotene color), wheat flour, eggs, sugar, vegetable oil (palm and canola oils), invert sugar, bakers yeast, egg whites, butterfat, wheat, gluten, salt, natural and artificial flavorings, skim milk, milk proteins, dough conditioners (mono - and diglycerides, diacetyl tartaric acid esters of mono - and diglycerides, sodium stearoyl lactylate), locust bean gum, dried yeast, calcium propionate (preservative), beta-carotene color.