1. Make Blueberry Preserves

2. Combine blueberries, sugar, and lemon juice in a medium saucepan over medium heat. Bring to a boil, then simmer 15 minutes, stirring occasionally and crushing some berries for thickness. Cool and refrigerate while preparing dough.

3.

4. Prepare Cream Cheese Filling

5. Beat softened cream cheese and sugar with an electric mixer until smooth and creamy, about 2 minutes. Set aside.

6.

7. Prepare Babka Dough

8. Whisk flour, 1/2 cup sugar, and salt in a bowl. In a stand mixer bowl fitted with dough hook, combine warm milk and 1 teaspoon sugar; sprinkle yeast on top and let foam 5 minutes. Add eggs, vanilla, and flour mixture; mix on low until combined, then medium-low 5 minutes until smooth. Add butter 1 tablespoon at a time, mixing on medium-low 4 minutes until sticky dough forms. Transfer to greased bowl, cover, and rise in warm spot 1-1.5 hours until doubled (or refrigerate overnight).

9.

10. Assemble Babkas

11. Punch down dough; divide in half. On floured surface, roll one half into 12×16-inch rectangle. Spread with half cream cheese (leave 1-inch border on one long edge), then half preserves. Roll tightly from borderless side into log; chill 30 minutes if sticky. Trim ends; slice lengthwise into 2 halves (cut sides up). Twist halves together, pinching ends. Repeat with second dough half. Place each in parchment-lined 9×5 loaf pan, cover, and rise 1 hour until puffed.

12.

13. Bake and Glaze

14. Preheat oven to 350°F. Bake 40 minutes until deep golden and tester is clean. Meanwhile, simmer sugar syrup ingredients until sugar dissolves; cool slightly. Brush hot babkas generously with syrup. Cool 10 minutes in pans, then transfer to wire rack.