In a mixing bowl, combine the flour, sugar, instant yeast, and salt until evenly mixed.

In a separate bowl, whisk together warm milk, eggs, and softened butter until smooth.

Gradually pour the wet ingredients into the dry ingredients, stirring until a sticky dough forms.

Turn the dough out onto a floured surface and knead for 5–7 minutes until smooth and elastic.

Place the dough in a greased bowl, cover with plastic wrap, and let rise at room temperature for about 1 hour or until doubled in size.

Meanwhile, prepare the filling by melting chocolate chips or mixing cocoa powder with a little butter until spreadable.

Roll the risen dough into a 12×18-inch rectangle, spread the chocolate filling evenly over the surface, then roll tightly into a log.

Slice the log lengthwise down the middle, twist the two halves together with the cut sides up, and place in a greased 9×5-inch loaf pan.

Cover the loaf pan and let the babka rise a second time for 30 minutes.

Preheat the oven to 350°F (175°C). Brush the top of the babka with melted butter.

Bake for 30 minutes or until golden brown and cooked through.

Remove from the oven, brush again with melted butter, and let cool completely before slicing.