To make the dough: Place the yeast and 1/2 teaspoon sugar in a small bowl. Add the lukewarm water and stir gently to mix. Set aside until foamy, 5 to 10 minutes. In a stand mixer fitted with a dough hook, mix together the flour, 1/3 cup sugar and 2 teaspoons vanilla.

In a medium saucepan, scald the milk (bring almost to a boil, until milk is just simmering). Allow to sit for 1 minute to cool just slightly.

With mixer on low, add the water-yeast mixture, milk and melted butter. Add eggs one at a time.

When the dough begins to come together after 2 to 3 minutes, turn off the mixer and scrape down the sides. Raise the speed to high and mix for another 5 to 10 minutes until the dough is shiny, elastic and smooth. It may seem like a long time to mix, but the result is worth the wait. (You can also knead vigorously by hand for 10 minutes if you don’t have a stand mixer.)

Place dough in a greased bowl with a damp towel on top. Allow to rise 1 to 2 hours.

Prepare the 3 greased loaf pans.

To make the crumb topping: Place all ingredients in a bowl. Using a wooden spoon, mix until crumbs form. Cut the dough into 3 equal parts (use a food scale for precision). Roll out one part into a rectangle. Spread with one-third each of the chocolate hazelnut spread, then marshmallow fluff, and then sprinkle with graham cracker crumbs and roll up along the shorter side.

Once the dough is formed into a swirled log, cut it straight down the middle so the filling is exposed. Cut 1/2 inch off each end. Layer each cut piece on top of one another and twist. Place in a greased loaf pan.

Repeat with the other 2 pieces of babka dough. Lightly drape a kitchen towel over the top of pans.

Allow to rise another 30 minutes. Preheat oven to 350 F. while the dough rises. Top with crumb topping. Bake for 30 minutes.

Allow to cool for 5 to 10 minutes. Using a butter knife, loosen sides of the babka from the pan and place on a wire rack to cool. Makes 3 babkas.