Gently warm the milk to 100 to 110°F (20 to 30 seconds in the microwave). Add the yeast and stir to combine. Set aside for about 5 minutes, or until the yeast begins to foam.

Meanwhile, combine 3 ¼ cups flour, sugar, and salt in the bowl of a stand mixer.

In a separate bowl, whisk together the pumpkin and eggs until combined.

Once the yeast is foamy, pour the pumpkin mixture into the dry ingredients and stir with a rubber spatula or wooden spoon. Add the milk/yeast mixture and stir until combined (some dry spots may remain).

Using the dough hook, begin kneading the dough on low speed. Gradually add in the butter, 1 tablespoon at a time. If you find that the butter is not incorporating into the dough, then knead slightly by hand. Continue to mix until the dough is smooth and plump, but not too sticky. This will take 4 to 5 minutes. If it is too sticky, add in more flour, up to an additional ½ cup or as needed.

Place the dough in a lightly greased bowl and cover with plastic wrap. Allow to rise in a draft-free room until doubled in size. This will take 1 to 2 hours.

Once the dough has doubled in size, turn it out onto a lightly floured surface. Roll the dough into a long rectangle, about 10 X 20-inches. Using an offset spatula, spread the dough with the chocolate-hazelnut paste. Sprinkle on the toasted hazelnuts and chocolate - making sure neither are too big or it will be difficult to cut.

Starting at the long edge, tightly roll up the dough into a log. Pinch the edges to seal. If the dough is at all soft, chill it covered in the refrigerator or freezer for up to 30 minutes.

Place the chilled dough on a piece of parchment paper. Using a serrated knife, slice the dough in half lengthwise to create two long ropes. Twist the two ropes together. Holding the two ends, wrap them around to form a wreath. Pinch the ends together to complete the circle. Lift the wreath with the parchment paper onto a baking sheet. Cover with plastic wrap or a kitchen towel for about 30 minutes, or until slightly puffed (it will not double in size).

Meanwhile, preheat the oven to 350°F. When ready, bake the babka wreath for 25 to 35 minutes, or until slightly golden on the edges and the thickest part reaches 190°F.