Combine milk, 1 tablespoon sugar, and yeast in a small bowl. Let stand until foamy, about 5 minutes.
Add remaining sugar, butter, and eggs to the milk mixture. Stir until mostly combined, but it won’t be smooth.
Measure flour, cardamom, and salt into the bowl of a stand mixer. Pour in wet ingredients and attach dough hook. Mix until dough comes together in a shaggy mass. Cover the stand mixer with a clean dish towel and let dough rest for 10 minutes.
Uncover the dough and knead on medium speed until smooth, about 5 minutes. Continue to knead on low speed until dough is soft, elastic, and shiny, about 5 minutes more. Transfer to an oiled bowl and cover with plastic wrap. Place in a warm spot until doubled in size, 1 to 1 1/2 hours.
Meanwhile, make the blueberry filling. Combine blueberries, sugar, and orange juice in a medium saucepan. Bring mixture to a low boil. Smash the blueberries with a potato masher. Continue to simmer until the mixture has thickened enough to spread, 15 to 20 minutes. Remove from heat and stir in extracts. Chill until completely cool.
Turn the dough out onto a lightly floured surface. Punch down and divide into 2 pieces. Roll 1 piece into a 9×18-inch rectangle, squaring off with a bench scraper as you roll to make it is as even as possible. Spread 1/2 of the blueberry filling over the dough, leaving about a 1-inch border. Roll up the dough into a tight roll, starting from the long edge closest to you. Pinch seams to seal. Repeat with the remaining dough and filling.
Place logs side by side on a lined baking sheet, cover with plastic wrap, and chill for 1 hour.
Use a sharp knife or bench scraper to each log in half, lengthwise, so you have 4 filled strips of dough on the baking sheet.
Place 2 strips across each other to form a plus sign. Arrange the remaining 2 strips to form an interlocking cross. Fold the end of the strip closest to you over the strip to its right. Repeat 3 more times, moving clockwise. Fold remaining strips over to the left, moving counterclockwise. Repeat folding step until only short ends remain; join ends and tuck them carefully under the braid.
Cover the braid and place in a warm place to rise for 45 minutes.
Preheat the oven to 350 degrees F (175 degrees C) towards the end of the second rise. 1
Beat egg with a pinch of salt and brush some over the braid. Sprinkle with pearl sugar. 1
Bake in the preheated oven until golden brown, about 35 minutes. Cool completely before slicing.