Activate Yeast: In the bowl of your mixer, combine warm milk, sugar, and yeast. Let it sit for 5–10 minutes until foamy.
Make the Dough: Add the flour, eggs, and salt. Knead with the dough hook until combined. Gradually add the softened butter, piece by piece, kneading until the dough is smooth and glossy (about 8–10 minutes).
First Rise: Cover the bowl and let the dough rise in a warm spot until doubled in size (about 1.5–2 hours).
Prepare the Swirl: While the dough rises, cook the raspberries, sugar, and lemon juice in a small saucepan over medium heat until thickened into a jammy consistency. Let it cool completely.
Roll and Fill: On a floured surface, roll the dough into a large rectangle. Spread the raspberry jam evenly over the surface.
Shape: Roll the dough tightly into a log, pinching the ends closed. Place into a greased loaf pan.
Second Rise: Let the loaf rise again in the pan for 45 minutes.
Bake: Brush the top with an egg wash (one egg beaten with a splash of milk). Bake at 350°F (175°C) for 30–35 minutes until golden and hollow when tapped.
Serve: Let it cool completely before slicing to ensure the swirl stays intact.