Combine 2 cups of fresh blueberries, ½ cup of sugar, and 1 tablespoon of lemon juice in a saucepan. Boil, then reduce to a simmer for about 15 minutes until thickened. Cool and refrigerate to firm up.

Beat together 8 oz of softened cream cheese and ¼ cup of sugar until smooth and creamy. Set aside for later use.

In a bowl, mix ½ cup of warm milk with 2 teaspoons of active dry yeast and let it proof for about 5-10 minutes until foamy. Combine this with 2 eggs, 1 teaspoon of vanilla extract, 4 cups of all-purpose flour, ¼ cup of sugar, and 1 teaspoon of kosher salt in a stand mixer.

Gradually add 4 tablespoons of very soft unsalted butter into the mixer until fully incorporated and the dough is smooth and elastic, approximately 5-7 minutes of mixing.

Cover the dough with a clean cloth and let it rise in a warm place for about 1-1.5 hours, or until it has doubled in size.

Punch down the dough, then divide it into two equal pieces. Roll each piece into a rectangle, spread half the cream cheese filling and blueberry preserves evenly over each rectangle, roll them up tightly, then twist into a braid shape.

Place the braids into parchment-lined loaf pans, cover, and let them rise again for about 1 hour until puffy.

Preheat the oven to 350°F (175°C) and bake the loaves for about 40 minutes, or until golden brown.

Brush the top with a sugar syrup made from ¼ cup of sugar and ¼ cup of water, which gives a beautiful glossy finish. Let the babkas cool in the pan for a few minutes before transferring to a wire rack.