Sift bread flour, cardamom powder, cinnamon, and salt. 

Warm the milk either in a sauce pan over stove or in microwave, until it reaches the 100 - 110 degrees. Add 1 tsp of sugar in the milk and give it a stir. Sprinkle the yeast over the milk and give a stir. Set aside for proofing. The yeast should foam up in 8-10 minutes. If it doesn't foam in 15 minutes, then discard the milk and start over. 

Meanwhile, in your standing mixer with dough hook attachment, add the sugar and orange zest. Rub the zest in the sugar with your fingers to release the citrus flavor. 

Add the sifted dry ingredients over the sugar and zest.

Then add the orange juice and start mixing at low speed (speed 1). Add the proofed yeast and milk mix.

Increase the speed to 2, and start adding the yolks and egg one at a time. mix for 7-8 minutes till eggs are well incorporated. The dough will feel very dry. That's quiet normal, as it will all come together once butter is added. However if its really dry, you could add 1/2 - 1 tsp water and check. But it won't be required.

Now start adding butter cubes one at a time. Total time to incorporate butter should with 15-20 minutes. This will help knee the dough and work the gluten.

Once the dough is all kneaded, wrap the bowl tightly with cling wrap. At this time you could put the bowl in refrigerator for over night. Then take it out and leave it at the counter for around 1 hour until it comes at room temperature. It should proof to almost double in size. Or, you could skip the refrigerator method and directly proof at room temperature for 3-4 hours. I personally prefer keeping it in refrigerator and meanwhile I can work on filling.  

Heat ghee in a wok and saute carrots and beets for 5 minutes on medium heat.

Meanwhile, Warm the milk either in microwave or on stove top. Add the warmed milk to the carrot mix and stir. Let it simmer for 10-15 minutes on low heat.

Add Cardamom pwd and saffron strand. Cook uncovered, while stirring till all the liquid evaporates and it gets thick. This process can take upto 45 minutes to an hour. 

Add the sugar and cook for another 10-15 minutes, as sugar will release liquid. 

Take off the heat and let it cool completely. Then store in air tight container in refrigerator. The halwa should be cold or room temp. to be filled in the dough. The halwa can be made months in advance and can be frozen. Thaw it completely before filling.

Put sugar in a saucepan. Add Water and bring to boil over medium heat. Once all the sugar is completely dissolved, take the pan off the heat.

Add cardamom powder and saffron strands in the hot water. Keep to aside to cool completely. 

Line 2 baking loaf pans with parchment paper, allowing 2-3 inches of overhang on both the longer sides.

Divide the dough into 2 equal parts.

Lightly flour the surface and roll one part into a rectangular of 16 inch by 14 inch approximately. Repeat this for the other part as well.

Spread approximately 125-150 grams of Halwa on each rolled out dough. Leave around 1 inch all around the edge. Do not overfill the dough with too much filling.

Sprinkle crushed pistachios on top of the halwa.

Brush egg wash on all around the edges.

Roll the dough tightly starting from the longer side. Once rolled, pinch the edges to seal the dough. Let it rest for 5-10 minutes, seal side down. This will help seal the dough properly. Repeat this for the other dough as well.

Using a serrated knife, cut the log lengthwise in the middle. if the dough is too soft, then chill for 10 minutes in refrigerator. This will make it easy to cut and braid.

With the filling side up, criss cross the 2 rolls to form a braid. Repeat this for the other filled log. 

Gently transfer the braids into the prepared pans, in such a way that the overhang dough folds into the centre to fit in the pan. Don't worry if the dough has gaps and is not sealed. The second proofing time will fill the gaps and seal everything. Repeat the same for the second log.

Cover both the pans with damp towel and let it proof at the counter for 2 hours. 

Preheat the oven at 350 degrees F.

Bake the babka loafs for 35-50 minutes, until golden brown. You can check by inserting the toothpick in the loaf and it should come out clean. However, I prefer checking the loaf with instant read thermometer, and it should read between 200-210 degrees F when done.

Immediately brush the cardamom saffron glaze on the hot loaf while still in the pan.

Cool on the wire rack for 30-40 minutes before slicing. The loaf or the slices can be frozen at this point.