In a small bowl, combine warm milk and a pinch of sugar, then sprinkle the yeast over the top. Let it sit for 5–10 minutes until foamy.

In a large mixing bowl, whisk together the flour, granulated sugar, and salt until evenly combined.

Add the foamy yeast mixture, softened butter, eggs, vanilla extract, and lemon zest (if using) to the dry ingredients. Mix until a shaggy dough forms.

Transfer the dough to a lightly floured surface and knead by hand for 10–12 minutes, until the dough becomes smooth and elastic. Add small amounts of flour if the dough is too sticky.

Place the kneaded dough in a lightly greased bowl. Cover with a damp towel and let rise in a warm area for 1 to 1 ½ hours, or until doubled in size.

While the dough rises, stir together raspberry preserves, cornstarch, and water in a small saucepan. Cook over medium-low heat, stirring constantly, until the mixture thickens slightly. Set aside to cool completely.

After the first rise, punch down the dough and roll it into a 10x15-inch rectangle on a floured surface.

Spread the cooled raspberry mixture evenly over the dough, leaving a ½-inch border on all sides.

Starting from one long edge, roll the dough into a tight log. Slice the log lengthwise down the center to reveal the layers, then twist the two halves together with the cut sides facing up.

Gently transfer the twisted dough into a greased 9x5-inch loaf pan. Cover and let rise for another 30–40 minutes.

While the loaf is rising, preheat your oven to 350°F (175°C).

Brush the top of the loaf with melted butter. Bake for 35–40 minutes until golden brown and fully baked. If it browns too quickly, cover loosely with foil for the final 10 minutes.

Let the baked loaf cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before glazing.

In a small bowl, whisk together powdered sugar, lemon juice, and milk until smooth. Drizzle over the cooled loaf.