In a small bowl, combine 1/4 cup warm milk heated to 110°F with 1 tablespoon granulated sugar and 2 teaspoons active dry yeast. Let sit for 5 to 10 minutes.

In a large bowl, whisk together remaining 1/4 cup sugar, 2 large eggs, and 1 teaspoon vanilla extract. Once yeast mixture is frothy, pour it into the wet ingredients and stir.

Gradually add 3 cups all-purpose flour and 1 teaspoon salt, stirring until a cohesive dough forms.

Flour a clean surface and knead dough for about 8 to 10 minutes until smooth and elastic.

Make a small indentation in the dough, add 4 tablespoons softened unsalted butter, and knead for an additional 5 minutes.

Place the dough into a greased bowl, cover with a kitchen towel, and let rise for 1 to 2 hours.

In a saucepan, combine 1 cup fresh raspberries, 1/3 cup raspberry jam, and 1 tablespoon lemon juice. Cook for about 5 minutes, then let cool.

After the dough has risen, punch it down and roll it out into a rectangle. Spread the cooled raspberry mixture evenly over the dough.

Roll the dough into a tight log, pinch the seams, and place seam-side down in a greased loaf pan. Cover and let rise for another 30 to 45 minutes.

Preheat oven to 350°F. Bake the loaf for 25 to 30 minutes until golden brown and a toothpick comes out clean.

Let the loaf cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.